WO2019004406A1

WO2019004406A1 - Diffraction optical element, manufacturing method therefor, acrylic resin composition for forming diffraction optical element, and illumination device

Info

Publication number: WO2019004406A1
Application number: PCT/JP2018/024734
Authority: WO
Inventors: 英範吉岡; 由紀子伴; ノリ子永松
Original assignee: 大日本印刷株式会社
Priority date: 2017-06-30
Filing date: 2018-06-28
Publication date: 2019-01-03
Also published as: JP2023029913A; JP7186524B2; JP2019012266A

Abstract

The present invention provides a diffraction optical element which has resistance to sticking under a wet heat condition, and in which a pattern is rarely torn, a manufacturing method therefor, an acrylic resin composition for forming the diffraction optical element, and an illumination device. This diffraction optical element shapes light from a light source, and is provided with, on at least one surface side of a transparent substrate, a diffraction grating part in which one or more high refractive index protruding sections protruding from the surface of the transparent substrate, and one or more low refractive index sections are disposed, wherein the high refractive index protruding section is formed by a cured product of an acrylic resin composition, and the storage elastic modulus (E') of the cured product at 60°C and a relative humidity of 95% is 0.90×109-2.6×109 Pa inclusive.

Description

Diffractive optical element and method of manufacturing the same, acrylic resin composition for forming diffractive optical element, and illumination device

The present disclosure relates to a diffractive optical element having sticking resistance under wet heat conditions and having a small amount of pattern burrs, a method of manufacturing the same, an acrylic resin composition for forming the diffractive optical element, and a lighting apparatus.

In recent years, the need for sensor systems has increased in recent years, such as the need for personal identification to avoid security risks through the spread of networks, the flow of automated driving of cars, and the spread of the so-called "Internet of Things". There is. There are various types of sensors, and the information to be detected is various. One of the means is that the light source emits light to the object and information is obtained from the reflected light. . For example, a pattern authentication sensor or an infrared radar is an example.

The light source of these sensors is used with wavelength distribution, brightness and spread according to the application. As the wavelength of light, visible light wavelengths to infrared light wavelengths are often used. In particular, infrared light is hard to be affected by external light, is invisible, and it is possible to observe the inside of the surface vicinity of an object. It is widely used. Moreover, as a type of light source, an LED light source, a laser light source, and the like are often used. For example, a laser light source with less spread of light is preferably used to detect a distant place, and an LED light source is preferably used to detect a relatively close place or to illuminate an area having a certain extent of spread. Be

The size and shape of the illuminated area on the object do not necessarily match the spread (profile) of the light from the light source, in which case it is necessary to shape the light with a diffuser, lens, shield, etc. is there. Recently, a diffuser called Light Shaping Diffuser (LSD) has been developed that can shape the shape of light to some extent.
Further, as another means of shaping light, a diffractive optical element (DOE) can be mentioned. This is an application of the diffraction phenomenon when light passes through a place where materials having different refractive indexes are arranged with periodicity. Although the DOE is basically designed for light of a single wavelength, it is theoretically possible to shape the light into almost any shape. Further, in the LSD described above, the light intensity in the irradiation area is a Gaussian distribution, whereas in the DOE, it is possible to control the uniformity of the light distribution in the irradiation area. Such characteristics of DOE are advantageous in terms of high efficiency by suppressing irradiation to unnecessary regions, downsizing of the apparatus by reduction of the number of light sources, and the like.
The DOE is applicable to both parallel light sources such as lasers and diffused light sources such as LEDs, and is applicable to a wide range of wavelengths from ultraviolet light to visible light and infrared light.

DOE requires microfabrication in nano order, and in particular, in order to diffract light of long wavelength, it has been necessary to form a fine shape with a high aspect ratio. Therefore, electron beam lithography technology using an electron beam is conventionally used to manufacture the DOE. For example, after forming a hard mask or a resist on a quartz plate transparent in the ultraviolet to near infrared regions, a predetermined shape is drawn on the resist using an electron beam, resist development, dry etching of the hard mask, dry of quartz After etching is sequentially performed to form a pattern on the surface of the quartz plate, the hard mask can be removed to obtain a desired DOE.

As a form of a diffractive optical element, a form called a grating cell array (grating cell array) is conventionally used. In the grating cell array type diffractive optical element, for example, square fine unit regions (cells) are arranged in a matrix. Then, in one unit area of the grating cell array type diffractive optical element, a diffraction grating whose rotation direction in the plane is directed in a fixed direction at a fixed pitch is arranged. Further, in the grating cell array type diffractive optical element, the pitches and rotational directions of the diffraction gratings arranged are different for each unit region, and one diffractive optical element is configured as an aggregate thereof.
Generally, a diffractive optical element based on this grating cell array is manufactured by patterning glass. The patterning of the glass generally includes a direct writing method such as a laser or an electron beam. This direct writing method is not suitable for mass production because it takes time to produce a diffractive optical element having a fine pattern of several μm or less because it draws one by one and is not widely used.

As a method of producing a diffractive optical element, there is a nanoimprinting method which is an alternative to the direct writing method (see Patent Document 1).
The nanoimprinting method is a method in which a master plate pattern is contact-transferred onto a replica plate, and a product of the same type as the master plate can be produced at high speed. However, the side to be transferred is not glass but resin material. That is, the replica plate to be a product is not patterned by glass but patterned by resin.
In addition, as a resin material used to form a microstructure pattern having an aspect ratio of 2 or more, an acrylic UV curable resin is generally known (see Patent Documents 2-3).

International Publication No. 2017/119400 JP, 2014-98864, A JP 2004-4515 A

However, when producing a diffractive optical element using a resin material by a nanoimprinting method, patterns are easily produced during sticking and release. Therefore, commercial manufacture of diffractive optical elements by nanoimprinting has been difficult in the prior art.
The above-mentioned acrylic UV curable resin has low heat resistance, and it is known that material deterioration occurs under high temperature conditions or high humidity conditions. In particular, under wet and high temperature conditions (hereinafter, such conditions are referred to as wet heat conditions), a phenomenon in which adjacent patterns are attached or separated by the meniscus force generated when water is released from between the fine patterns (Sticking) may be confirmed. If only the heat resistance is a problem, measures to improve the crosslink density of the resin or to make the resin multifunctional may be considered, but these measures can not eliminate the sticking.
On the other hand, when the crosslink density of the resin is improved or the resin is polyfunctionalized, as a result of the improvement of the film hardness after curing, pattern peeling may occur at the time of mold release.

The present disclosure has been accomplished in view of the above-described situation regarding the case of manufacturing a diffractive optical element other than the direct drawing method, and is a diffractive optical element having sticking resistance under wet heat conditions and having less pattern burrs and the same An object of the present invention is to provide a manufacturing method, an acrylic resin composition for forming a diffractive optical element, and a lighting device.

The diffractive optical element of the present disclosure is a diffractive optical element that shapes light from a light source, and includes at least one surface side of a transparent substrate, one or more high refractive index convex portions protruding from the surface of the transparent substrate, The high-refractive-index convex portion is formed of a cured product of an acrylic resin composition, and the high-refractive-index convex portion is formed at 60 ° C. and relative to the cured product. The storage elastic modulus (E ′) at a humidity of 95% is characterized by being 0.90 × 10 ⁹ Pa or more and 2.6 × 10 ⁹ Pa or less.

In the manufacturing method of the present disclosure, a diffraction grating portion in which one or more high refractive index convex portions protruding from the surface of the transparent base and one or more low refractive index portions are disposed on at least one surface side of the transparent base And a method of manufacturing a diffractive optical element that shapes light from a light source,
Preparing a mold having a cavity shape for forming the high refractive index convex portion and the low refractive index portion;
A cured product sample obtained by irradiating an acrylic resin composition to a cavity of the mold, and curing the acrylic resin composition with ultraviolet light so that the integrated light amount is 1,000 mJ / cm ² . Filling an acrylic resin composition having a storage elastic modulus (E ′) at 60 ° C. and a relative humidity of 95% of 0.90 × 10 ⁹ Pa or more and 2.6 × 10 ⁹ Pa or less,
A step of curing the acrylic resin composition by bringing the transparent substrate and the acrylic resin composition into contact with each other on the side of the cavity opening of the mold and irradiating active energy rays; Forming a diffraction grating portion having a high refractive index convex portion formed of a cured product of an acrylic resin composition on a transparent substrate by pulling the mold away from the substrate;
It is characterized by having.

In the acrylic resin composition of the present disclosure, one or more high refractive index convex portions protruding from the surface of the transparent substrate and one or more low refractive index portions are disposed on at least one side of the transparent substrate. An acrylic resin composition for forming a high refractive index convex portion of a diffractive optical element including a diffraction grating portion and shaping light from a light source, wherein an integrated light amount is 1,000 mJ relative to the acrylic resin composition. The storage elastic modulus (E ') at 60 ° C. and 95% relative humidity of a cured product sample obtained by curing by irradiation with ultraviolet light so as to be 1 cm ² / cm ² is 0.90 × 10 ⁹ Pa or more 2.6 × 10 It is characterized by being ⁹ Pa or less.

In the present disclosure, the storage elastic modulus (E ′) at 30 ° C. and a relative humidity of 30% of the cured product of the acrylic resin composition may be 1 × 10 ⁸ Pa or more and 5 × 10 ⁹ Pa or less.
In the present disclosure, the ratio (tan δ (= E ′ ′ / E ′)) of loss elastic modulus (E ′ ′) to storage elastic modulus (E ′) at 60 ° C. and 95% relative humidity of the cured product of the acrylic resin composition May be 0.12 or less.
In the present disclosure, it is preferable that the acrylic resin composition contains a urethane bond from the viewpoint of excellent sticking resistance under wet heat conditions and less pattern burrs.
In the present disclosure, the acrylic resin composition is an active energy ray curable resin composition containing a tetrafunctional or higher functional (meth) acrylate and a bifunctional (meth) acrylate, which is resistant to sticking under moist heat conditions. It is preferable from the point that it is excellent in quality and less in pattern pattern.

In the present disclosure, the active energy ray-curable resin composition contains 40% by mass or more and 80% by mass or less of the (meth) acrylate having four or more functional groups with respect to all the curable components, and the bifunctional (meth) It is preferable to contain 10% by mass or more and 60% by mass or less of acrylate from the viewpoint of excellent sticking resistance under wet heat conditions and less pattern burrs.

In the present disclosure, it is preferable that the tetrafunctional or higher functional (meth) acrylate contains a tetrafunctional or higher functional urethane (meth) acrylate from the viewpoint of excellent sticking resistance under wet heat conditions and less pattern unevenness.
In this case, the tetrafunctional or higher urethane (meth) acrylate is formed of the isocyanate group of the polyvalent isocyanate compound and the hydroxyl group of a compound having one hydroxyl group and two or more (meth) acrylic groups in the molecule. It is preferable that the compound is a urethane-bonded compound from the viewpoint of excellent sticking resistance under wet heat conditions and less pattern mottle.

In the present disclosure, it is preferable that the bifunctional (meth) acrylate has a molecular weight (Mw) of 100 or more and 5,000 or less from the viewpoint of excellent sticking resistance under wet heat conditions and less pattern burrs. .

In the present disclosure, a cured product of the acrylic resin composition as measured by a Vickers hardness test performed according to JIS Z 2 244 (2003) and under a measurement condition of maximum load 0.2 mN and holding time 10 seconds. It is preferable from the point which is further excellent in the sticking resistance under moist heat conditions that the restoration ratio of is 60% or more.

In the present disclosure, it is preferable that the high refractive index convex portion have a portion having a height of 400 nm or more from the viewpoint of being able to diffract light having a relatively long wavelength.
In the present disclosure, the top of the high refractive index convex portion is defined as the upper end, and the position of the valley bottom between the high refractive index convex portion and another high refractive index convex portion adjacent thereto, or the high refractive index convex portion Among the positions of the flat part closest to the top of the high-refractive-index convex part, the lower end of the high-refractive-index convex part is defined as the lower end of the high-refractive-index convex part When the ratio of the height of the high refractive index convex portion to the width of the high refractive index convex portion at a position corresponding to half the height is defined as the aspect ratio of the high refractive index convex portion, the high refractive index convex portion The aspect ratio is preferably 2 or more from the viewpoint of being able to diffract relatively long wavelength light.

An illumination device according to an embodiment of the present disclosure includes a frame having a conductive portion capable of supplying power from the outside and an opening serving as a light emitting surface, a light source, and the above-described diffractive optical element, and the light source is fixed in the inner space of the frame. And the diffractive optical element is disposed in the opening.
At this time, the light source may be a light source emitting an infrared ray having a wavelength of 780 nm or more.

According to the present disclosure, the storage elastic modulus (E ′) under moist heat conditions for the cured product of the acrylic resin composition forming the high refractive index convex portion is within the specific range, so sticking under the moist heat conditions is It can be prevented and the pattern can be reduced.

FIG. 1 is a plan view schematically showing an embodiment of a diffractive optical element. FIG. 1 is a schematic perspective view of an embodiment of a diffractive optical element. It is a figure which shows one Embodiment of a diffractive optical element, and is sectional drawing which shows typically an example of the A-A 'cut surface of FIG. FIG. 5 is a cross-sectional view schematically showing another embodiment of the diffractive optical element in which a base 3 is present between the transparent base 1 and the diffraction grating portion 2. FIG. 7 is a cross-sectional view schematically showing another embodiment of the diffractive optical element, in which the covering layer 5 is provided on the opposite side of the transparent base 1 with the diffraction grating portion 2 interposed therebetween. FIG. 7 is a cross-sectional view schematically showing another embodiment of the diffractive optical element, in which the covering layer 5 is provided on the opposite side of the transparent base 1 with the diffraction grating portion 2 interposed therebetween. FIG. 6 is a cross-sectional view schematically showing another embodiment of the diffractive optical element in which the low refractive index resin 3 is filled in the low refractive index portion 3; FIG. 6 is a cross-sectional view schematically showing another embodiment of the diffractive optical element in which the low refractive index resin 3 is filled in the low refractive index portion 3; FIG. 10 is a cross-sectional view schematically showing an embodiment including the anti-reflection layer 9 which is another embodiment of the diffractive optical element. FIG. 10 is a cross-sectional view schematically showing an embodiment including the anti-reflection layer 9 which is another embodiment of the diffractive optical element. It is a figure which is provided for explanation of an aspect ratio, and is a fragmentary sectional view of a diffraction grating part containing a high refractive index convex part of binary shape. FIG. 6 is a view provided for describing an aspect ratio, and is a schematic partial cross-sectional view of a diffraction grating portion including multi-step (4-level) high refractive index convex portions. FIG. 7 is a cross-sectional view schematically showing an embodiment in which the thickness of the high refractive index convex portion 2 a is intermittently increased from the tip to the root, which is another embodiment of the cross-sectional shape of the diffraction grating portion. FIG. 10 is a cross-sectional view schematically showing an embodiment in which the thickness of the high refractive index convex portion 2 a is continuously increased from the tip to the root, which is another embodiment of the cross-sectional shape of the diffraction grating portion. FIG. 10 is a cross-sectional view schematically showing an embodiment in which the high refractive index convex portions 2a have a multistage shape (4-level), which is another embodiment of the cross-sectional shape of the diffraction grating portion. FIG. 7 is a cross-sectional view schematically showing another embodiment of the cross-sectional shape of the diffraction grating portion, in which the high refractive index convex portion 2a has a multi-stage shape (8-level). FIG. 5 is a schematic perspective view showing that the irradiation light 21 is diffracted by the diffractive optical element 10 and a square image 24 is formed at the center of the screen 22. FIG. FIG. 5 is a schematic perspective view showing that the irradiation light 21 is diffracted by the diffractive optical element 10 and a square image 24 is formed on the top of the screen 22. FIG. It is a front view of screen 22 shown to FIG. 10A. It is a front view of the screen 22 shown to FIG. 10B. It is a schematic diagram of an example of the metal mold | die used for the manufacturing method of this indication. FIG. 7 is a schematic cross-sectional view showing an example of the acrylic resin composition filling step in the manufacturing method of the present disclosure, and showing a state in which the acrylic resin composition 32 is placed on the surface of the mold 31. FIG. 7 is a schematic cross-sectional view showing an example of the acrylic resin composition filling step in the manufacturing method of the present disclosure, and showing a state of applying the acrylic resin composition 32 to the surface of the mold 31. It is a schematic diagram of an example of the acrylic resin composition hardening process in the manufacturing method of this indication. It is a schematic diagram of an example of the mold release process in the manufacturing method of this indication. It is a sectional view showing typically one embodiment of a lighting installation. It is a perspective view showing a case where light which becomes circular [irradiation area 23] is projected directly to screen 22 of plane shape. FIG. 6 is a schematic perspective view of the diffractive optical element 50 in which sticking has occurred. It is a cross-sectional schematic diagram of the diffractive optical element which water infiltrated between the fine patterns. It is a cross-sectional schematic diagram of the diffractive optical element in which sticking occurred. It is a cross-sectional schematic diagram which shows a mode that pattern peeling arose during manufacture of a diffractive optical element.

Hereinafter, although the diffractive optical element of the present disclosure and a method of manufacturing the same, an acrylic resin composition for forming the diffractive optical element, and a lighting apparatus will be described in detail in order, the present disclosure is limited to the following embodiments. Instead, various modifications may be made within the scope of the present invention.
In the present disclosure, the shapes and geometrical conditions as well as the degree of them are specified. For example, terms such as “parallel” and values of length and angle etc. It shall be interpreted including the extent to which the function can be expected. In addition, the term “plan view” in this specification means that the image is viewed from the direction perpendicular to the top surface of the diffractive optical element. In general, “plan view” corresponds to visual recognition from the direction perpendicular to the surface of the diffractive optical element having the diffraction grating portion (corresponding to the direction of the plan view as shown in FIG. 1).
In the present disclosure, the active energy ray is not only visible light and electromagnetic waves of wavelengths in the invisible region such as ultraviolet light and X-rays, but also curing of acrylic resin compositions that collectively refers to particle rays such as electron rays and alpha rays. It contains radiation with energy quanta that is sufficient to As active energy rays, ultraviolet rays are preferred.
In the present disclosure, (meth) acrylic represents each of acrylic or methacrylic, (meth) acrylate represents each of acrylate or methacrylate, and (meth) acryloyl represents each of acryloyl or methacryloyl.
In the present disclosure, “shaping the light” means that the shape (irradiation area) of the light projected onto the target object or the target area is made to be an arbitrary shape by controlling the traveling direction of the light. . For example, by transmitting light (FIG. 14) in which the irradiation area 23 is circular when projected directly onto the flat screen 22 (FIG. 14A), the irradiation area is square (24 in FIG. 10A). It means having a target shape, such as a rectangle, a circle (not shown), or the like.
In the present disclosure, light emitted from the light source is transmitted through the diffractive optical element and emitted as it is without being diffracted as zero-order light (25 in FIG. 10A), and diffracted light generated by the diffractive optical element is referred to as first-order light (26a to 26d in FIG. 10A).
In the present disclosure, the cross-sectional shape of the diffraction grating portion is defined as that in which the diffractive optical element is placed on a horizontal surface. In the example of FIG. 2, the X axis is taken in the repetition direction of the periodic structure, orthogonal to the X axis, the Y axis taken so that XY forms a horizontal plane, and the Z axis taken in the direction perpendicular to the XY horizontal plane. In the present disclosure, a valley bottom (minimum point of Z) between convex portions is a reference of height 0, and a portion of height 0 is a concave portion. Further, in the present disclosure, a portion having a height H (H> 0) is a convex portion. On the other hand, in the present disclosure, the depth to the valley bottom between the protrusions may be referred to as the maximum height of the protrusions, but in the present disclosure, the height and the depth have a relationship between front and back, and the protrusions In the case of focusing on the height, the case of focusing on the recess, and the depth, it is substantially the same.
In the present disclosure, it is a binary (2-level) shape that the cross-sectional shape of the diffraction grating portion is a repetitive structure of a concave portion with a height of 0 and a convex portion with a height H as shown in the example of FIG. It is said that. Further, in the present disclosure, in the cross-sectional shape of the diffraction grating portion, a convex portion having two or more flat portions (substantially horizontal portions) may be referred to as a multistage shape, and the multistage convex portion and the concave portion are combined to n If there are two flats, it may be called n-level shape.
Further, in the present disclosure, “transparent” refers to one that transmits light of at least a target wavelength. For example, even if it does not transmit visible light, if it transmits infrared rays, it shall be treated as transparent when used for infrared applications.

1. Diffractive Optical Element The diffractive optical element according to the present disclosure is a diffractive optical element that shapes light from a light source, and includes at least one high refractive index convex projecting from the surface of the transparent base on at least one surface side of the transparent base Portion and one or more low refractive index portions are provided, and the high refractive index convex portion is formed of a cured product of an acrylic resin composition, and the cured product of the cured product The storage elastic modulus (E ') at 0 ° C and a relative humidity of 95% is characterized by being 0.90 × 10 ⁹ Pa or more and 2.6 × 10 ⁹ Pa or less.
Hereinafter, the physical properties of the cured product forming the high refractive index convex portion, which is a main feature of the present disclosure, will be described, and then the structure of the diffractive optical element will be described.

(1) Cured Product of Acrylic Resin Composition The high refractive index convex portion in the diffractive optical element of the present disclosure is an acrylic resin having a specific storage elastic modulus (E ′) under the conditions of 60 ° C. and 95% relative humidity. It is formed of a cured product of the composition. Thus, by having an appropriate storage elastic modulus (E ') under moist heat conditions, it is possible for the diffraction grating portion in the diffractive optical element to prevent sticking and to reduce pattern burrs. The mechanism is described below.

FIG. 2 is a schematic perspective view of an embodiment of a diffractive optical element. In this embodiment, high-refractive-index convex portions 2 a connected in a long and thin manner are arranged on one surface side of the transparent base material 1 at a constant interval. DOE and GCA usually have such a so-called line & space structure.
On the other hand, FIG. 15 is a schematic perspective view of a diffractive optical element in which sticking has occurred. In FIG. 15, hatched portions indicate portions where sticking has occurred. Unlike in FIG. 2, in the diffractive optical element of FIG. 15, all or part of adjacent high refractive index convex portions 2 a are sticking and are in contact with each other. As described above, in the DOE or GCA, since the long and thin convex portions are arranged in a fine size, the sticking that has once occurred is easily propagated as a whole compared to the dot-like moth-eye structure and the like. In particular, since GCA is usually smaller in size than DOE, sticking is more likely to occur.

As described above, the term "sticking" is a phenomenon derived from the meniscus force generated when moisture is released from between the fine patterns of the diffractive optical element.
FIG. 16A is a schematic cross-sectional view showing a state in which water has infiltrated between fine patterns of the diffractive optical element. FIG. 16B is a schematic cross-sectional view of the diffractive optical element in which the sticking has occurred, corresponding to a part of the BB ′ cut surface in FIG.
In FIG. 16A, the diffractive optical element 10 provided with the diffraction grating portion 2 on the transparent substrate 1 is depicted. The diffraction grating portion 2 includes a high refractive index convex portion 2a and a low refractive index portion 2b, and in the example of FIG. 16A, the low refractive index portion 2b is air. However, as shown in FIG. 16A, the moisture 51 infiltrates into one of the low refractive index portions 2b. In this case, the stress σ acting on the high refractive index convex portion 2a in contact with the moisture 51 is expressed by the following formula (1).
Formula (1) σ = (6γ cos θ / D) × (H / W) ²
(In the above equation (1), σ is stress, γ is surface tension, θ is contact angle, D is the line pattern interval, H is the height of the high refractive index convex portion, W is the high refractive index Indicates the width of the projection, respectively)
When the stress σ exceeds a certain value, the high refractive index convex portions 2a fall in the stress direction, and the adjacent high refractive index convex portions 2a are in contact with each other to cause sticking (FIG. 16B). When the water 51 evaporates, the stress σ disappears, so the sticking is canceled and the high refractive index convex portion 2a in contact may be separated, but the high refractive index convex portion 2a is fused together particularly under wet heat conditions In some cases, sticking may not be eliminated.
In order to prevent sticking, it is required that the material forming the high refractive index convex portion be so hard that it can withstand stress σ.

As shown in FIG. 15 to FIG. 16B, the high refractive index convex portion has a portion extending in a ridge line shape (a portion extending narrowly in the surface direction and linearly extending), and extends in a ridge line shape of the high refractive index convex portion Stucking is particularly likely to occur when at least a portion of the portions are separated by low refractive index portions having a width narrower than the height of the high refractive index convex portions and adjacent in parallel or substantially in parallel.
In the manufacturing process of a diffractive optical element and a product including the same, assembly may be performed under wet heat conditions. In addition, even when the diffractive optical element after completion is placed under moist heat conditions, there is a possibility that the fine pattern can not be maintained as the sticking generated in a part of the diffraction grating portion is chained and expanded as a whole. See Figure 15). Thus, the avoidance of sticking is particularly important in order to form and maintain the desired fine pattern.

However, if the high refractive index convex portion is merely hard, pattern peeling occurs at the time of mold release. Here, “pattern wrinkling” means that a part of the entire or a part of the high refractive index convex portions forming the fine pattern in the diffraction grating portion is broken or taken off from the root. means.
FIG. 17 is a schematic cross-sectional view showing a state in which pattern peeling has occurred at the time of mold release of the diffractive optical element. Such a pattern is found, for example, in the case of replicating a diffractive optical element by imprinting with a resin using a mold prepared by electron beam lithography.
When pulling the convex cured resin 102 on the substrate 101 away from the mold 103, if the cured resin 102 is too hard, the cured resin 102 may break in the mold 103. It is necessary for the cured resin 102 to be deformed to a certain extent at the time of mold release, but when the resin cured product 102 is too hard, free deformation can not be expected, and as a result, the load required for mold release increases. It is considered that breakage occurs in a portion where particular load concentrates. When the cured resin material 102 is broken, high refractive index convex portions having a desired height can not be obtained as illustrated.
Such a problem of pattern peeling is not limited to the cured resin on the molded diffractive optical element. For example, in the case of using a resin mold for molding a diffractive optical element, there is also a problem of pattern thinning also for the convex portion on the resin mold.
On the other hand, when the resin cured product 102 is easily deformed, it is considered that the resin cured product 102 is stuck without being able to endure expansion and contraction at the time of mold release, although it is easy to release the mold.

Thus, the desired fine pattern can not be obtained when the high refractive index convex portions are too hard or too soft. As a result of studies by the present inventors, high refractive index convex portions are formed of a cured product of an acrylic resin composition, and the storage elastic modulus (E ′) of the cured product at 60 ° C. and 95% relative humidity is 0. It became clear that sticking could be prevented under moist heat conditions and that the pattern could be suppressed from mold release at the time of mold release when it is not less than 90 × 10 ⁹ Pa and not more than 2.6 × 10 ⁹ Pa.
When the storage elastic modulus (E ') at 60 ° C. and 95% relative humidity of the cured product is less than 0.90 × 10 ⁹ Pa, sticking under moist heat conditions can not be avoided, and the fine pattern of the diffraction grating portion Can not maintain. In addition, when the storage elastic modulus (E ') under the moist heat condition is too low as described above, the cured product is excessively deformed at the time of mold release, resulting in sticking.
On the other hand, when the storage elastic modulus (E ′) exceeds 2.6 × 10 ⁹ Pa, the cured product lacks flexibility, and as a result of breakage at the time of mold release, pattern peeling occurs.

The cured product has a relative humidity of 60 ° C. and a relative humidity of 95 because it can prevent sticking under moist heat conditions, suppress breakage and breakage of the cured product, and is excellent in releasability and deformation during release. The storage elastic modulus (E ') in% is preferably 1.0 × 10 ⁹ Pa or more and 2.5 × 10 ⁹ Pa or less, and more preferably 1.1 × 10 ⁹ Pa or more and 2.3 × 10 ⁹ Pa or more. ^{It is 9} Pa or less, and more preferably 1.2 × 10 ⁹ Pa or more and 2.0 × 10 ⁹ Pa or less.

In the said patent document 1, using the hardened | cured material whose storage elastic modulus (E ') in 25 degreeC is a predetermined value is described. The storage elastic modulus (E ') under moist heat conditions in the present disclosure is a physical property that is completely different from the storage elastic modulus (E') at 25 ° C. Further, while the problem of the above-mentioned Patent Document 1 is to simply obtain a diffractive optical element excellent in durability, the problem of the present disclosure is a diffraction which has anti-sticking properties under wet heat conditions and which has less pattern burrs. It is to obtain an optical element, and also differs in terms of problems.

The storage elastic modulus (E ′) is a physical property that does not depend on the shape or size of the object to be measured. In the present disclosure, it is measured with a test piece cut out from a diffractive optical element, or with a test piece obtained by separately polymerizing an acrylic resin composition.
In the present disclosure, the storage elastic modulus (E ′) is measured by the following method in accordance with JIS K7244. First, a test piece for measurement is prepared. The test piece is obtained by cutting out the appropriate dimension from the diffraction grating portion of the diffractive optical element. Alternatively, the acrylic resin composition is sufficiently cured by irradiating ultraviolet light so that the integrated light amount is 1,000 mJ / cm ² , thereby obtaining a single film of an appropriate size, which is used as a test piece. It can also be done.
Next, the storage elastic modulus at 60 ° C. and 95% relative humidity is measured by measuring the dynamic viscoelasticity based on the conditions of the measurement temperature 60 ° C. and the relative humidity 95% and the measurement conditions shown in Table A in the examples. (E ') is required. Alternatively, the storage elastic modulus at 30 ° C. and 30% relative humidity is measured by measuring the dynamic viscoelasticity based on the conditions of measurement temperature 30 ° C. and relative humidity 30% and the measurement conditions shown in Table A in the examples. E ') is required. As a measurement device, for example, Rheogel E4000 manufactured by UBM can be used.
Alternatively, an indenter can be pressed into the surface of the test piece to determine the storage elastic modulus (E ′) of the surface of the test piece. As a measurement apparatus, for example, an AFM (Atomic Force Microscope) nano indenter such as TI950 TRIBOINDENTER manufactured by Hysitron can be used.
Measurement with an AFM nanoindenter has the advantage that the surface mechanical strength of the diffractive optical element surface can be measured directly. However, in this measurement, in order to prevent variations in measured values, it is preferable to measure by pressing an indenter in the vicinity of the center of the high refractive index convex portion. If a recess on the surface of a diffractive optical element is selected as a measurement location, the width of a Berkovich indenter usually used in an AFM nanoindenter often can not penetrate to the bottom of the recess, so the bottom of the recess is selected. Surface mechanical strength is difficult to measure. Further, in the peripheral portion of the high refractive index convex portion, the high refractive index convex portion is expected to be bent by the pressing of the indenter, so that it is difficult to obtain an accurate measurement value of the surface mechanical strength. As described above, it is difficult to stably obtain an accurate value except near the center of the high refractive index convex portion due to influences other than the material characteristics, so it is preferable to select the central portion of the high refractive index convex portion as the measurement place.
The outline of the measurement in the case of using the AFM nanoindenter is as follows. First, the measurement sample is set on the stage, and the measurement position is confirmed by the CCD camera. Next, after performing calibration as appropriate, the sample is moved under a Berkovich indenter to obtain an AFM image of the surface of the diffractive optical element in a dynamic force mode (DFM mode). The high refractive index convex portion is specified from the obtained AFM image, and several places around the center of the high refractive index convex portion are selected to be the measurement place. At this measurement site, measurement is performed by the contact mode of AFM. Examples of measurement conditions are shown below. The indentation hardness H _IT can be determined based on the relationship between the displacement and the load obtained at the load unloading time. This indentation hardness H _IT, storage modulus of interest (E ') is obtained.
<Measurement conditions>
Control method Displacement control Measurement depth 50 nm
・ Load application time 10 seconds ・ Holding time 5 seconds ・ Load unloading time 10 seconds ・ Indenter Burko Bitch indenter ・ Measurement temperature 30 ° C
・ Relative temperature 30%

However, in practice, it is difficult to obtain a test piece having a relatively large area as described above from the diffraction grating portion of the diffractive optical element. Then, the method of calculating | requiring storage elastic modulus (E ') using the test piece of acrylic resin composition single film is realistic.
The storage elastic modulus of the base adjacent to the high refractive index convex portion on the diffractive optical element is approximately the same value as the storage elastic modulus of the test piece obtained by curing the acrylic resin composition. The storage modulus (E ′) of the test piece obtained by curing the composition is the same as the storage modulus (E ′) of the high refractive index convex portion on the diffractive optical element.

The storage elastic modulus (E ′) at 30 ° C. and 30% relative humidity of the cured product of the acrylic resin composition may be 1 × 10 ⁸ Pa or more and 5 × 10 ⁹ Pa or less.
By using a cured product having the above storage elastic modulus (1 × 10 ⁸ Pa or more and 5 × 10 ⁹ Pa or less) under normal temperature and normal humidity conditions, the physical properties necessary for the diffractive optical element can be satisfied under the conditions. By selecting from among such cured products those which meet the condition of storage elastic modulus under the above-mentioned wet heat condition (0.90 × 10 ⁹ Pa or more and 2.6 × 10 ⁹ Pa or less), the moist heat condition A diffractive optical element having anti-sticking resistance in the lower part and with less pattern blurring can be obtained.

In the present disclosure, it is also important to specify the storage elastic modulus (E ′) under high humidity conditions of 95% relative humidity. The high humidity condition is considered to be a factor of sticking because it causes excessive moisture in the diffraction grating portion of the diffractive optical element (the above-mentioned FIG. 16A and FIG. 16B). Furthermore, the high temperature condition of 60 ° C. is considered to be a factor for promoting sticking, since it promotes the supply of water to the diffraction grating portion. Therefore, storage elastic modulus (E ') under moist heat conditions of 60 ° C. and 95% relative humidity is important in examining the sticking resistance.
In other technical fields, for example in the field of semiconductors, it is known that moisture causes sticking in the grooves of the semiconductor surface. However, in the case of a semiconductor, since the material can not be changed, a countermeasure is taken to prevent sticking by removing water from the groove on the surface of the semiconductor in advance. Here, as a method of removing water, there is known a method of applying the easily volatilizable organic solvent such as isopropanol to the semiconductor surface and changing the surface tension of the water in the groove to facilitate the removal of the water. .
On the other hand, in the case of the diffractive optical element of the present disclosure, it is possible to adjust the material (the cured product of the acrylic resin composition) constituting the diffraction grating portion. Therefore, the composition of the acrylic resin composition is adjusted so that the storage elastic modulus (E ′) at 60 ° C. and 95% relative humidity is 0.90 × 10 ⁹ Pa or more and 2.6 × 10 ⁹ Pa or less. Thus, it is possible to obtain an optimum diffractive optical element having sticking resistance.

The contact angle of water on the surface of the diffraction grating portion is preferably 90 degrees or more, more preferably 100 degrees or more, and even more preferably 110 degrees or more. When the surface of the cured product of the acrylic resin composition has the water repellency as described above, water is less likely to adhere to the surface of the diffraction grating portion, and sticking is less likely to occur.
The measuring method of the contact angle of water is as follows. A droplet of 2.0 μL is dropped with the surface of the diffraction grating portion of the diffractive optical element up, and the contact angle after 0.5 seconds of deposition is measured. As a measuring apparatus, for example, a contact angle meter DM 500 manufactured by Kyowa Interface Science Co., Ltd. can be used.
When the composition of the acrylic resin composition which is the raw material of the cured product forming the diffraction grating portion is known, the contact angle of water is determined using the cured product of the acrylic resin composition having the composition. It may be measured.
First, the acrylic resin composition is coated on a transparent substrate, and the acrylic resin composition is cured by irradiation with ultraviolet light so that the integrated light amount becomes 1,000 mJ / cm ² , and the coating is performed. Form a film. With the coated film side as the upper surface, it is horizontally attached to a black acrylic plate with an adhesive layer. Next, a 2.0 μL water droplet is dropped onto the coating, and the contact angle after 0.5 seconds of deposition is measured. The measuring device is the same as above.

As a physical property corresponding to sticking resistance, the glass transition of the acrylic resin composition used for formation of a diffraction grating part in "5. Glass transition temperature (Tg) measurement of acrylic resin composition" of the Example mentioned later Temperature Tg (degreeC) is mentioned.
From the viewpoint of having sticking resistance, the glass transition temperature Tg may be 45 ° C. or more and 80 ° C. or less, and may be 48 ° C. or more and 79 ° C. or less.
However, in the present disclosure, the glass transition temperature Tg is a secondary index. In the present disclosure, the storage elastic modulus (E ′) at 60 ° C. and 95% relative humidity is the most important parameter for exhibiting the effect of the anti-sticking effect and the effect of preventing the pattern cracking. When it is difficult to determine the presence or absence of these two effects by this storage elastic modulus (E '), the two of the two are used with the glass transition temperature Tg and the recovery rate of the cured product of the acrylic resin composition described later as an index. Determine if there is an effect.

The acrylic resin composition preferably contains a urethane bond, because it is easy to obtain a diffractive optical element having sticking resistance under wet heat conditions and having few patterns. Moreover, it is preferable that the said acrylic resin composition is an active energy ray curable resin composition containing the (meth) acrylate more than tetrafunctional and the bifunctional (meth) acrylate from the same reason.
Among these, tetrafunctional or higher urethane (meth) acrylates tend to increase the storage elastic modulus (E ′) of the resulting cured product under moist heat conditions, and the bifunctional urethane (meth) acrylate is a obtainable cured product. There is a tendency to lower the storage modulus (E ') under the heat and humidity conditions of Therefore, the storage elastic modulus (E ') of the resulting cured product under moist heat conditions can be adjusted to a desired value, so that a diffractive optical element having sticking resistance under wet heat conditions and having a small pattern haze can be obtained. From the viewpoint of easiness, the acrylic resin composition is more preferably an active energy ray curable resin composition containing a tetrafunctional or higher functional urethane (meth) acrylate and a bifunctional urethane (meth) acrylate.

It is preferable that the active energy ray-curable resin composition does not contain as much as possible a material that is susceptible to moisture or a material that absorbs water and tends to swell. This is because the sticking resistance of the resulting diffractive optical element may be reduced if the material contains a large amount of such materials.
Examples of the material susceptible to moisture include known materials that decompose by reacting with water. Moreover, as a material which absorbs water and tends to swell, for example, a material having high hydrophilicity can be mentioned, and more specifically, vinyl pyrrolidone, ammonium acrylate, carboxyethyl acrylate and the like can be mentioned.
The total content of the material sensitive to moisture and the material which easily absorbs water and swells is preferably 10% by mass or less, based on 100% by mass of the whole active energy ray-curable resin composition. Is 5% by mass or less, more preferably 1% by mass or less, and particularly preferably 0% by mass.

Hereinafter, each component contained in an active energy ray curable resin composition is demonstrated.
The tetrafunctional or higher (meth) acrylate means a polyfunctional acrylate having four or more (meth) acryloyl groups in one molecule. The tetrafunctional or higher (meth) acrylates include both monomers and polymers.
Examples of tetrafunctional or higher (meth) acrylates include pentaerythritol tetra (meth) acrylate, dipentaerythritol hexa (meth) acrylate, urethane hexa (meth) acrylate, dipentaerythritol tetra (meth) acrylate, and ditrimethylolpropane tetratetra Examples thereof include (meth) acrylates, oligoester tetra (meth) acrylates, and dipentaerythritol polyacrylates; ethylene oxide-modified compounds thereof, propylene oxide-modified compounds, and ε-caprolactone-modified compounds. In particular, with respect to the ethylene oxide modified compound, the propylene oxide modified compound, and the ε-caprolactone modified compound, the modified number n ≦ 6 is preferable. This is because in the case of the modification number n> 6, the cured product of the active energy ray curable resin composition tends to be too soft and sticking may easily occur. These tetrafunctional or higher functional (meth) acrylates can be used alone or in combination of two or more.
The content of the tetrafunctional or higher (meth) acrylate is preferably 40% by mass or more and 80% by mass or less, and more preferably 55% by mass or more and 65% by mass with respect to all the curable components of the active energy ray curable resin composition. It is more preferable that the content is less than%.

The tetrafunctional or higher functional (meth) acrylate is a tetrafunctional or higher functional urethane from the viewpoint of enhancing the shape retention and heat resistance of the obtained diffractive optical element by increasing the crosslink density by chemical bonding and densifying the network structure. It is preferred to contain meta) acrylate. There are no particular limitations on the position and number of urethane bonds in this case, and whether or not the (meth) acryloyl group is at the end of the molecule. Particularly preferred are compounds having 6 or more (meth) acryloyl groups in the molecule, and more preferred are compounds having 10 or more. The upper limit of the number of (meth) acryloyl groups in the molecule is not particularly limited, but is preferably 15 or less. If the number of (meth) acryloyl groups in the urethane (meth) acrylate molecule is too small, the curability of the resulting cured product may be reduced, and the storage modulus may be reduced. On the other hand, when the number of (meth) acryloyl groups in the urethane (meth) acrylate molecule is too large, the consumption rate of carbon-to-carbon double bonds of the (meth) acryloyl group by polymerization, that is, the reaction rate may not be sufficiently increased.

The structure of the tetrafunctional or higher urethane (meth) acrylate is not particularly limited, but from the viewpoint of excellent sticking resistance under wet heat conditions and less pattern mottle, the isocyanate group of the polyvalent isocyanate compound (a), It is preferable that it is a compound in which one hydroxyl group and a hydroxyl group of the compound (b) having two or more (meth) acrylic groups in the molecule are urethane-bonded.
Here, it is preferable that substantially all of the isocyanate groups in the polyvalent isocyanate compound (a) form a urethane bond with the hydroxyl group in the compound (b).

There is no particular limitation on the polyvalent isocyanate compound (a) in this case, and a compound having two or more isocyanate groups in the molecule can be mentioned. Examples of compounds having two isocyanate groups in the molecule include 1,5-naphthyl diisocyanate, 4,4′-diphenylmethane diisocyanate, hydrogenated diphenylmethane diisocyanate, 1,3-phenylene diisocyanate, 1,4-phenylene diisocyanate , Tolylene diisocyanate, butane-1,4-diisocyanate, hexamethylene diisocyanate, 2,2,4-trimethylhexamethylene diisocyanate, 2,4,4-trimethylhexamethylene diisocyanate, cyclohexane-1,4-diisocyanate, xylylene diisocyanate , Isophorone diisocyanate, lysine diisocyanate, dicyclohexylmethane-4,4'-diisocyanate, 1,3-bis (isocyanatomethyl) cyclo Hexane, methylcyclohexane diisocyanate, m- tetramethylxylylene diisocyanate, and the like. Moreover, as a compound having three isocyanate groups in the molecule, for example, trimethylolpropane adduct adduct, biuret, isocyanate formed by modifying isophorone diisocyanate, tolylene diisocyanate, hexamethylene diisocyanate, xylylene diisocyanate, etc. A nurate body etc. are mentioned. Among these, isophorone diisocyanate, tolylene diisocyanate, hexamethylene diisocyanate and the like are particularly preferable in the present disclosure.

The compound (b) having one hydroxyl group and two or more (meth) acrylic groups in the molecule is not particularly limited, but a compound having three or more (p) hydroxyl groups in the molecule Examples of the compound in which (meth) acrylic acid is reacted (p-1) with the hydroxyl group of b-1); and compounds in which glycidyl (meth) acrylate and (meth) acrylic acid undergo ring opening reaction.

Here, in the case where the “compound (b) having one hydroxyl group and two or more (meth) acrylic groups in the molecule” (b) ”is produced by partially reacting two or more compounds with the compound In addition, the case where a compound having two or more hydroxyl groups is mixed in the molecule, and the case where a compound having one (meth) acrylic group is mixed are included.

In the compound (b), “a compound in which (meth) acrylic acid is reacted (p-1) times with a compound (b-1) having p (p is an integer of 3 or more) hydroxyl groups in the molecule” There are no particular limitations on the “compound (b-1) having three or more hydroxyl groups in the molecule”, and examples thereof include glycerin, trimethylolethane, trimethylolpropane, pentaerythritol, tetramethylolethane, diglycerin and ditriol. Methylol ethane, ditrimethylol propane, dipentaerythritol, ditetramethylol ethane; ethylene oxide-modified compounds thereof; propylene oxide-modified compounds thereof; ethylene oxide-modified compounds of isocyanuric acid, propylene oxide-modified compounds, ε-caprolactone-modified compounds; Ester etc. .

The number of hydroxyl groups in the compound (b-1) is particularly preferably 4 or more, and more preferably 6 or more, in that the number of functional groups in the resulting urethane (meth) acrylate can be increased. Specifically, for example, diglycerin, ditrimethylolethane, ditrimethylolpropane, dipentaerythritol, ditetramethylolethane and the like are particularly preferable.

In the case of diglycerin, for example, (meth) acrylic acid is reacted with three hydroxyl groups of four hydroxyl groups of diglycerin to give one hydroxyl group and two or more hydroxyl groups (in this case) A compound (b) having three (meth) acrylic groups is synthesized. Furthermore, when the case where polyvalent isocyanate compound (a) is isophorone diisocyanate is taken as an example, the compound which has one said hydroxyl group and two or more (meth) acryl groups in two isocyanate groups of isophorone diisocyanate. Two (b) react with each other to synthesize “a tetrafunctional or higher urethane (meth) acrylate”. At this time, if the compound (b) having one hydroxyl group and three (meth) acrylic groups in the molecule reacts with isophorone diisocyanate, as a result, it has six (meth) acrylic groups in the molecule [4] A functional or higher urethane (meth) acrylate "is synthesized.

The bifunctional (meth) acrylate means a polyfunctional acrylate having two (meth) acryloyl groups in one molecule.
Specific examples of the difunctional (meth) acrylate include, for example, 1,4-butanediol di (meth) acrylate, 1,6-hexanediol di (meth) acrylate, 1,9-nonanediol di (meth) acrylate Etc. straight chain alkanediol di (meth) acrylates;
Ethylene glycol di (meth) acrylate, diethylene glycol di (meth) acrylate, triethylene glycol di (meth) acrylate, tetraethylene glycol di (meth) acrylate, polyethylene glycol di (meth) acrylate (polyethylene glycol # 200 di (meth) acrylate) Polyethylene glycol # 300 di (meth) acrylate, polyethylene glycol # 400 di (meth) acrylate, polyethylene glycol # 600 di (meth) acrylate etc., dipropylene glycol di (meth) acrylate, tripropylene glycol di (meth) acrylate , Tetrapropylene glycol di (meth) acrylate, polypropylene glycol # 400 di (meth) acrylate, polypropylene glyco Alkylene glycol di (meth) acrylates such as Le # 700 di (meth) acrylate;
Partial (meth) acrylic acid esters of trihydric or higher alcohols such as pentaerythritol di (meth) acrylate, pentaerythritol di (meth) acrylate monostearate and pentaerythritol di (meth) acrylate monobenzoate;
Bisphenol A di (meth) acrylate, tetrabromobisphenol A di (meth) acrylate, bisphenol S di (meth) acrylate, EO modified bisphenol A di (meth) acrylate, PO modified bisphenol A di (meth) acrylate, hydrogenated bisphenol A Di (meth) acrylate, EO modified hydrogenated bisphenol A di (meth) acrylate, PO modified hydrogenated bisphenol A di (meth) acrylate, bisphenol F di (meth) acrylate, EO modified bisphenol F di (meth) acrylate, PO modified Bisphenol-based di (meth) acrylates such as bisphenol F di (meth) acrylate and EO-modified tetrabromobisphenol A di (meth) acrylate;
Neopentyl glycol di (meth) acrylate, neopentyl glycol PO modified di (meth) acrylate; hydroxypivalic acid neopentyl glycol ester di (meth) acrylate, caprolactone adduct of hydroxypivalic acid neopentyl glycol ester di (meth) acrylate; 1,6-Hexanediol bis (2-hydroxy-3-acryloyloxypropyl) ether; tricyclodecane dimethylol di (meth) acrylate, isocyanuric acid EO modified di (meth) acrylate; propylene di (meth) acrylate; phthalic acid Di (meth) acrylate; di (meth) acrylates such as tricyclodecanemethanol di (meth) acrylate and the like can be mentioned. These difunctional (meth) acrylates can be used alone or in combination of two or more.
The content of the bifunctional (meth) acrylate is preferably 10% by mass or more and 60% by mass or less, and 30% by mass or more and 45% by mass or less based on all the curable components of the active energy ray curable resin composition. It is more preferable that

The molecular weight (Mw) of the bifunctional (meth) acrylate is preferably 100 or more and 5,000 or less, from the viewpoint that the cured product of the active energy ray curable resin composition has an appropriate hardness, and is more preferable. 100 or more and 4,000 or less, more preferably 100 or more and 2,000 or less. When the molecular weight (Mw) of the bifunctional (meth) acrylate is 100 or more, as a result of the cured product having appropriate flexibility, the sticking resistance of the resulting diffractive optical element becomes better. In addition, when the molecular weight (Mw) of the bifunctional (meth) acrylate is 5,000 or less, as a result of the cured product being able to maintain an appropriate hardness, it is difficult to form a pattern in the obtained diffractive optical element.

The difunctional (meth) acrylate may contain a difunctional urethane (meth) acrylate. The content of the bifunctional urethane (meth) acrylate is preferably 30% by mass or less, and more preferably 20% by mass or less, based on all the curable components of the active energy ray curable resin composition. The content is more preferably 10% by mass or less, and particularly preferably 0% by mass.
The difunctional (meth) acrylate may contain a difunctional (meth) acrylate other than the difunctional urethane (meth) acrylate. The content of the bifunctional (meth) acrylate other than the bifunctional urethane (meth) acrylate is 10% by mass or more and 50% by mass or less with respect to the entire curable component of the active energy ray curable resin composition Is preferable, and 20 to 45% by mass is more preferable.

The bifunctional urethane (meth) acrylate is preferably a bifunctional urethane (meth) acrylate having one (meth) acrylic group at each end of the molecule.
There is no particular limitation on the chemical structure of the bifunctional urethane (meth) acrylate, and the weight average molecular weight is preferably 1,000 to 30,000, and 2,000 to 5,000. Is particularly preferred. If the molecular weight is too low, the flexibility may decrease, and if the molecular weight is too high, it may lead to a decrease in storage modulus.

The bifunctional urethane (meth) acrylate is not particularly limited, but the following are particularly preferable. That is, the diisocyanate compound (d) is reacted with both ends of the polymer or oligomer (c) such as hydroxyl group and amino group at both ends, and the obtained “polymer or oligomer having isocyanate group at both ends” is further added It is particularly preferable to react the compound (e) having a hydroxyl group and a (meth) acrylic group in the molecule at its both terminals.

The polymer or oligomer (c) having hydroxyl groups at both ends is not particularly limited, and examples thereof include ester oligomers, ester polymers, urethane oligomers, urethane polymers, polyethylene glycol, polypropylene glycol and the like. Among these, particularly preferred are ester oligomers and ester polymers. The molecular weight of such an oligomer or polymer is not particularly limited, but a weight average molecular weight of 1,000 to 5,000 is preferable in view of curability, and 2,000 to 3,000 is particularly preferable.

The diol component of the above-mentioned ester is not particularly limited, but ethylene glycol, propylene glycol, 1,4-butanediol, 1,6-hexanediol, diethylene glycol, triethylene glycol, tetraethylene glycol, 2,2'-thiodiethanol Etc. Particularly preferred are 1,4-butanediol, 1,6-hexanediol and the like.

The dicarboxylic acid component of the ester is not particularly limited, and examples thereof include alkylene dicarboxylic acids such as oxalic acid, succinic acid, maleic acid and adipic acid; and aromatic dicarboxylic acids such as terephthalic acid and phthalic acid. Particularly preferred are adipic acid and terephthalic acid.

There is no particular limitation on the diisocyanate compound (d) to be reacted at both ends of the polymer or oligomer, and the same diisocyanate compounds as those described in the item of the polyvalent isocyanate compound (a) above can be used. Particularly preferred is isophorone diisocyanate and the like.

Furthermore, the “compound (e) having a hydroxyl group and a (meth) acrylic group in the molecule, which is reacted at both ends of the polymer or oligomer having an isocyanate group at both ends obtained above, is not particularly limited, For example, 2-hydroxyethyl (meth) acrylate, 2-hydroxypropyl (meth) acrylate, ethylene glycol mono (meth) acrylate, propylene glycol mono (meth) acrylate and the like can be mentioned.

The active energy ray-curable resin composition contains monofunctional (meth) acrylate and / or trifunctional (meth) acrylate besides tetrafunctional (meth) acrylate and bifunctional (meth) acrylate. It may be. The monofunctional (meth) acrylate means an acrylate having one (meth) acryloyl group in one molecule. The trifunctional (meth) acrylate means a polyfunctional acrylate having three (meth) acryloyl groups in one molecule.
However, the lower the content of monofunctional (meth) acrylate and trifunctional (meth) acrylate, the better. Specifically, the total content of monofunctional (meth) acrylate and trifunctional (meth) acrylate is 10% by mass or less with respect to the total curable component of the active energy ray curable resin composition. Is preferable, 5% by mass or less is more preferable, and 0% by mass is more preferable.
Examples of monofunctional (meth) acrylates include phenoxyethyl acrylate, trimethylcyclohexanol acrylate, isobornyl acrylate, phenylphenol acrylate, nonylphenol acrylate and the like.
Examples of trifunctional (meth) acrylates include glycerin PO-modified tri (meth) acrylate, trimethylolpropane tri (meth) acrylate, trimethylolpropane EO-modified tri (meth) acrylate, trimethylolpropane PO-modified tri (meth) Acrylate, EO modified triisocyanurate (meth) acrylate, EO modified isocyanurate E-caprolactone modified tri (meth) acrylate, 1,3,5-triacryloylhexahydro-s-triazine, pentaerythritol tri (meth) acrylate, di- Pentaerythritol tri (meth) acrylate tripropionate and the like can be mentioned.

As for the curable component in the active energy ray-curable resin composition, the crosslinking density depending on the magnitude of the molecular weight may contribute to the determination of the storage elastic modulus under wet heat conditions.

The acrylic resin composition may contain one or more photopolymerization initiators, if necessary. The content of the photopolymerization initiator is usually 0.2 to 15% by mass, preferably 0.3 to 13% by mass, based on the total solid content of the acrylic resin composition. It is more preferable that the content be 10% by mass.
The photopolymerization initiator is not particularly limited, but known ones conventionally used for radical polymerization, such as acetophenones, benzophenones, alkylaminobenzophenones, benzyls, benzoins, benzoin ethers, benzyl Aryl ketone photopolymerization initiators such as dimethyl acetals, benzoyl benzoates, α-acyloxime esters; sulfur-containing photo polymerization initiators such as sulfides and thioxanthones; acyl phosphine oxides such as acyl diaryl phosphine oxides; Anthraquinones etc. are mentioned. Moreover, a photosensitizer can also be used together.

The acrylic resin composition preferably contains a release agent (material having releasability). The mold release agent can suppress the pattern of the cured product by improving the release property of the cured product of the acrylic resin composition. At the same time, the storage elastic modulus (E ') at 60 ° C. and 95% relative humidity of the cured product is 0.90 × 10 ⁹ Pa or more 2.6 × 10 ⁹ by appropriately selecting the type of the release agent. It can be adjusted to the range of Pa or less, and the cured product can also be provided with sticking resistance. That is, the release agent brings about a better effect in both of the suppression of the pattern scum and the sticking prevention in the cured product.
In addition, at the stage of forming the cured product of the acrylic resin composition, the addition of the release agent can prevent the reduction of the mold life due to the resin clogging at the time of release.
The release agent is not particularly limited as long as it is usually used for producing a diffractive optical element. The mold release agent can be appropriately selected from known mold release agents such as silicone type, fluorine type, and phosphoric acid type as needed, and used. Further, as these releasing agents, those fixed to the cross-linked structure of the acrylic resin composition and those existing in a free state can be selected according to the application.
Among them, as the release agent, non-reactive silicone, reactive silicone, and phosphoric acid-based release agent are preferably used, and among these, non-reactive silicone is more preferable.
As non-reactive silicones, KF-352A, KF-354L, KF-4003, KF-412, KF-413, KF-414, KF-415, KF-4701, KF-4917, KF-53, KF-54 , KF-6004, KF-643, KF-7235B, X-22-1877, X-22-2516, X-22-7322, PC-88A (trade name, manufactured by Shin-Etsu Silicone Co., Ltd.), TEGO Glide 100, TEGO Glide 410, TEGO Glide 432, TEGO Glide 435, TEGO Glide 440, TEGO Glide 450, TEGO Glide ZG400 (trade name, manufactured by Evonik Japan) and the like.
As reactive silicones, KF-2012, KF-393, KF-684, KF-8002, KF-8004, KF-8021, KF-8021, KF-860, KF-861, KF-865, KF-867, KF-868, KF-869, KF-869, KF-877, KF-880, KF-89, KF-99, KF-9901, X-22-170, X-22-173, X-22-174, X-22-176, X-22-2404, X-22-2426, X-22-3939A (all trade names, manufactured by Shin-Etsu Silicone Co., Ltd.), TEGO Rad 2010, TEGO Rad 2011, TEGO Rad 2100, TEGO Rad 2200 N, TEGO Rad 2250, TEGO Rad 2300, TEGO Rad 2500, TEGO Rad 2 650, TEGO Rad 2700, TEGO Rad 2800 (trade names, manufactured by Evonik Japan Co., Ltd.) and the like.

The acrylic resin composition only needs to contain at least the above-mentioned active energy ray curable component, and may further contain other components as necessary.
As other components, a plurality of antistatic agents, ultraviolet light absorbers, infrared light absorbers, light stabilizers, antioxidants and the like can be added. Antistatic agents are effective in preventing dust deposition during processing and use, and ultraviolet absorbers, infrared absorbers, light stabilizers and antioxidants are effective in improving durability. In the case of adding a material that absorbs light, it is necessary to take care not to affect the target wavelength of the diffractive optical element. For the purpose of improving heat resistance, compounding with an inorganic material such as silsesquioxane is also effective.
In addition, although it is preferable that the acrylic resin composition does not substantially contain a solvent in consideration of the environment, it contains a solvent in consideration of adhesion to a substrate, adjustment of viscosity, improvement of surface quality, etc. It is also good. When the solvent is contained, the resin is applied to the substrate or the mold, and the solvent is dried and then shaped.
Furthermore, the acrylic resin composition may contain a resin other than the acrylic resin. The acrylic resin composition is, for example, a compound having an ethylenically unsaturated double bond other than an acrylic resin, specifically, vinyl such as triethylene glycol divinyl ether, 2- (2-vinyloxyethoxy) ethyl acrylate, etc. You may contain a system compound etc.

The diffractive optical element of the present disclosure preferably has excellent reflow resistance. Here, “excellent reflow resistance” means that the mass change rate before and after heating (for example, 260 ° C. for 1.5 minutes) is 2% or less, and the transmittance fluctuation before and after the heating is 1% or less. means.
As shown in “(5) Other steps” of “2. Method of manufacturing diffractive optical element” described later, in the case of manufacturing an illumination device using the diffractive optical element, a temporary assembly including the diffractive optical element is used. The process (reflow process) put into a reflow oven and heated on high temperature conditions may be implemented. By this reflow process, the light source and the frame surrounding the same can be electrically connected to the mounting substrate by, for example, solder or the like, and the lighting device can be efficiently manufactured.
However, in the reflow process, since a high temperature of 200 ° C. or higher is instantaneously applied to the material constituting the lighting device, the material may be dissolved or sublimated. In particular, when the high refractive index convex portion in the diffraction grating portion forms a fine structure, in the case where the cured product of the acrylic resin composition constituting the high refractive index convex portion easily dissolves or sublimes easily As a result of the deformation of the shape of the high refractive index convex portion, there is a possibility that the transmittance fluctuation may occur in the diffractive optical element. Moreover, even if the shape of the high refractive index convex portion is maintained, when the cured product of the acrylic resin composition is decomposed, the mass of the high refractive index convex portion may be reduced.
Therefore, the diffractive optical element of the present disclosure preferably has excellent reflow resistance. The diffractive optical element having excellent reflow resistance can be said to be excellent in formability because the shape of the high refractive index convex portion is not easily damaged in the reflow step.
As a diffractive optical element having excellent reflow resistance, for example, a diffractive optical element in which a cured product of an acrylic resin composition containing a tetrafunctional or higher functional (meth) acrylate is used to form a high refractive index convex portion is It can be mentioned.

The calculation method of mass change rate and transmittance fluctuation is as follows.
(Calculation method of mass change rate of diffractive optical element)
The mass of the diffractive optical element before and after the reflow is measured, and the mass change rate a is calculated from the following formula I.
Formula I a = {(M ₀ -M ₁ ) / M ₀ } × 100
(In the above formula I, a represents a mass change rate (%), M ₀ represents a mass of the diffractive optical element before reflow (mg), and M ₁ represents a mass of the diffractive optical element after reflow (mg).)
(Method of calculating transmittance fluctuation of diffractive optical element)
The transmittance (%) of the diffractive optical element before and after reflow is measured. The transmittance is measured using an ultraviolet visible near infrared (UV-Vis-NIR) spectrophotometer (for example, UV-3150 manufactured by Shimadzu Corporation). The transmittance of the transparent base and the diffraction grating portion of the diffractive optical element having a wavelength of 850 nm is measured by this device.
The absolute value of the difference between the transmittance of the diffractive optical element before reflow and the transmittance of the diffractive optical element after reflow is taken as the transmittance fluctuation (%) of the diffractive optical element.

The refractive index of the cured product of the acrylic resin composition constituting the high refractive index convex portion is not particularly limited, but is preferably 1.4 to 2.0 and 1.45 to 1.8. More preferable. According to the present disclosure, a shape having an aspect ratio of 2 or more can be stably formed, and a favorable diffractive optical element can be obtained even with a resin having a lower refractive index than silicon oxide and the like.
Further, in the present disclosure, the transmittance of the cured product of the resin composition constituting the high refractive index convex portion is not particularly limited, but the infrared transmittance (wavelength 850 nm) is preferably 90% or more, 92% or more It is more preferable that

From the viewpoint of suppressing sticking, the ratio (tan δ (= E ′ ′) / E ′) of loss elastic modulus (E ′ ′) to storage elastic modulus (E ′) at 60 ° C. and 95% relative humidity of a cured product of acrylic resin composition ) Is preferably 0.12 or less, more preferably 0.11 or less, and still more preferably 0.10 or less. When the ratio (tan δ (= E ′ ′ / E ′)) under wet heat conditions is 0.12 or less, the contribution of elasticity is higher than the contribution of viscosity in the cured product of the acrylic resin composition, The diffractive optical element has excellent sticking resistance under wet heat conditions because the cured product exhibits the property as an elastic body more strongly.
The loss modulus (E ′ ′) at 60 ° C. and 95% relative humidity of the cured product of the acrylic resin composition can be measured by the same method as the storage modulus (E ′).

It is preferable that the restoration rate of the hardened | cured material of an acrylic resin composition is 60% or more. It is because a cured product having such a recovery rate has better resistance to sticking.
The acrylic resin in the acrylic resin composition preferably contains a urethane bond, and more preferably contains a tetrafunctional or higher functional urethane (meth) acrylate, from the viewpoint that the recovery rate is 60% or more.

The measurement conditions of the recovery rate are as follows.
As a cured product of the acrylic resin composition to be used for the measurement of recovery rate, a test piece cut out from a diffractive optical element may be used, or a test piece obtained by separately polymerizing the acrylic resin composition is used. It is also good. The method of preparing these test pieces is as described above.
Based on JIS Z 2244 (2003), the Vickers hardness test is carried out under the following measurement conditions. Specifically, an indenter is pressed into the surface of the test piece under the following measurement conditions, and the recovery rate (%) of the surface of the test piece is measured. As a measuring device, for example, PICODENTER HM-500 manufactured by Fisher Instruments can be used.
<Measurement conditions>
・ Maximum load 0.2mN
・ Loading speed 0.2 mN / 10 sec ・ Holding time 5 seconds ・ Load unloading speed 0.2 mN / 10 sec ・ Indenter Vickers indenter ・ Measuring temperature 25 ° C

(2) Structure of Diffractive Optical Element FIG. 1 is a plan view schematically showing an embodiment of the diffractive optical element of the present disclosure. FIG. 2 is a perspective view schematically showing an embodiment of the diffractive optical element of FIG. FIG. 3 is a cross-sectional view schematically showing an example of a cross section taken along line AA ′ of FIG.
As shown in FIG. 3, the diffractive optical element 10 of the present disclosure includes the diffraction grating portion 2 on one surface side of the transparent substrate 1. The diffraction grating portion 2 includes one or more high refractive index convex portions 2 a protruding from the surface of the transparent substrate 1 and one or more low refractive index portions 2 b. As shown in FIG. 3, when two or more high refractive index convex portions 2 a and two or more low refractive index portions 2 b are used, they are arranged so as to alternately appear periodically.
The diffraction grating portion 2 may be provided on one side of the transparent substrate 1 or may be provided on both sides of the transparent substrate 1.
The diffractive optical element of the present disclosure generally has a plurality of regions (for example, 2A to 2D regions in FIG. 1) having different periodic structures. In the example of FIG. 1, the partial periodic structure 2A to 2D is a binary (2-level) of concavities and convexities (for example, the diffraction grating portion 2 of FIG. 3), but the shape of the region is required to shape the light as desired. The depth must be designed appropriately.

4 to 7B are cross-sectional views schematically showing other embodiments of the diffractive optical element of the present disclosure.
FIG. 4 shows an embodiment in which a base 3 is present between the transparent substrate 1 and the diffraction grating portion 2. When two or more high refractive index convex portions 2 a are used, the high refractive index convex portions 2 a may be isolated from each other (FIG. 3), or the high refractive index convex portions 2 a may be separated by the base 3. It may be connected (FIG. 4). When the high refractive index convex portion 2a is formed using a mold as described later, actually, a very thin base 3 is formed on the transparent substrate 1, as shown in FIG. Therefore, the diffractive optical element 10 may include such a base 3.
FIGS. 5A and 5B show an embodiment in which the covering layer 5 is provided on the opposite side of the transparent substrate 1 with the diffraction grating portion 2 interposed therebetween. The covering layer 5 may be in direct contact with the diffraction grating portion 2 or may be provided on the diffraction grating portion 2 via an adhesive layer (adhesive layer). Note that adding the covering layer 5 to the embodiment shown in FIG. 3 corresponds to the embodiment shown in FIG. 5A, and adding the covering layer 5 to the embodiment shown in FIG. 4 corresponds to the embodiment shown in FIG. 5B. Do.
6A and 6B show an embodiment in which the low refractive index portion 3 is filled with the low refractive index resin 7. From the viewpoint of increasing the refractive index difference, the low refractive index portion is preferably air. On the other hand, the low refractive index portion 3 is preferably made of the low refractive index resin 7 from the viewpoint that a diffractive optical element excellent in mechanical strength can be obtained. The low refractive index resin 7 added to the embodiment shown in FIG. 3 corresponds to the embodiment shown in FIG. 6A, and the low refractive index resin 7 added to the embodiment shown in FIG. 4 is shown in FIG. 6B. It corresponds to the embodiment.

7A and 7B show an embodiment in which the anti-reflection layer 9 is provided on the opposite side of the diffraction grating portion 2 with the transparent substrate 1 interposed therebetween. By providing the anti-reflection layer 9 in this manner, it is possible to suppress the reflected light and to improve the light utilization efficiency. The antireflective layer 9 may be provided in direct contact with the transparent substrate 1, or another member (such as a glass layer or an adhesive layer) may be interposed between the antireflective layer 9 and the transparent substrate 1. May be The embodiment shown in FIG. 3 with the addition of the antireflection layer 9 corresponds to the embodiment shown in FIG. 7A, and the embodiment shown in FIG. 4 with the addition of the antireflection layer 9 shown in FIG. 7B. It corresponds to the embodiment.

It is preferable that the high refractive index convex portion have a portion having an aspect ratio of 2 or more, which is conceptualized as “the ratio of height to width” or “the length of the protrusion”.
A diffractive optical element including a high refractive index convex portion having an aspect ratio of 2 or more can obtain diffracted light of a desired shape even if it is an infrared ray (for example, an infrared ray of 780 nm or more) having a longer wavelength than conventional It is possible to suppress zero-order light in diffracted light. Also, as described later, it is preferable that the diffractive optical element having a relatively large aspect ratio as described above is a transmissive diffractive optical element.

However, in the present disclosure, the high refractive index convex portion may have a binary shape or a multistage shape. For example, FIG. 8A is a schematic cross-sectional view of a binary high-refractive-index convex part, and FIG. 8B is a schematic cross-sectional view of a multi-level (4-level) high-refractive-index convex. The root 41 of the high refractive index convex portion 2a may be a transparent base material or a base.
Therefore, the aspect ratio of the high refractive index convex portion in the present disclosure is defined as follows.
First, as shown in FIG. 8A, the aspect ratio when the high refractive index convex portion has a binary shape is as follows: (height H of high refractive index convex portion) / (half of height of high refractive index convex portion) It is defined as the width W) of the high refractive index convex portion at the position of the height (H / 2). Here, the height H of the high refractive index convex portion means the height difference from the top of the high refractive index convex portion to the concave portion (the position of the valley bottom between the adjacent high refractive index convex portions) .
Further, as shown in FIG. 8B, the aspect ratio when the high refractive index convex portion has a multi-stage shape is as follows: (height H of high refractive index convex portion) / (minimum processing width W _min of high refractive index convex portion) It is defined as Here, the minimum processing width W _min of the high refractive index convex portion in the present disclosure is a portion corresponding to the height h in the figure as shown in FIG. 8B, that is, the middle belly of the high refractive index convex portion having a multistage shape. Focusing on the portion from the flat portion at the highest position among the flat portions at the top to the top of the high refractive index convex portion of the multistage shape, at the half height position (h / 2) of this portion It is defined as the width. In other words, as shown in FIG. 8B, the uppermost flat portion (height: H) of the high refractive index convex portion is the upper end, and the flat portion of the second stage from the top of the high refractive index convex portion The width at half height (h / 2) from the lower end with the height: H−h) as the lower end is the minimum processing width W _min of the high refractive index convex portion.
Therefore, in the present disclosure, the “aspect ratio of the high refractive index convex portion” in a broad sense, which includes both the high refractive index convex portion having the binary shape and the high refractive index convex portion having the multistage shape, The top of the high refractive index convex portion is defined as the upper end, and the position of the valley bottom between the high refractive index convex portion and another high refractive index convex portion adjacent thereto, or the closest from the top of the high refractive index convex portion When the one closer to the top of the high refractive index convex portion among the positions of the flat portion is defined as the lower end, the height from the lower end to the upper end of the high refractive index convex portion corresponds to half the height difference between the upper end and the lower end It is defined as the ratio of the height of the high refractive index convex portion to the width of the high refractive index convex portion.
By defining the aspect ratio in this manner, it is possible to design the diffraction grating portion precisely in an optical manner, and to correlate the correlation between the ease of removal of the high refractive index convex portion from the mold and the aspect ratio of the high refractive index convex portion. It can be raised.
The height H, the width W, and the minimum processing width W _min of the high refractive index convex portion can be calculated from, for example, an SEM image of the cross-sectional shape of the diffraction grating portion.

In general, the shape of the diffraction grating is determined by the wavelength of light, the refractive index (difference) of the material through which light is transmitted, and the required diffraction angle. For example, in the case of using a material having a refractive index of 1.5 in the air and making the laser light vertically incident on the side of the diffraction grating portion of the diffractive optical element, the groove depth of the diffraction grating is optimum as the wavelength of light becomes longer. It becomes deeper, and a 850 nm depth is required for infrared rays of wavelength 850 nm. That is, in the diffractive optical element of the present disclosure, in the cross-sectional shape of the diffraction grating portion, the high refractive index convex portion preferably includes a portion having a height of 850 nm or more, and curing shrinkage (eg, 10%) by active energy rays It is more preferable that the height is 944 nm or more in consideration of the above, and it is preferable that the height be about 994 nm in consideration of the manufacturing error (for example, 5%).
Also, in order to diffract light in the direction of a diffraction angle of 30 °, the aspect ratio of the high refractive index convex portion is about 1.1, and for diffracting in the direction of 70 °, the aspect ratio of about 2.1 is sufficient. .
However, this is a case where light is diffracted in only one direction, and when actually used as a light source of a sensor, it is necessary to spread diffracted light uniformly over a predetermined area. For this purpose, it is necessary to combine regions having various diffraction angles and diffraction directions in a complicated manner, but as a result, a region in which the pitch is narrowed to λ / 4 is included. Here, since the optimum depth of the diffraction grating is determined by the wavelength of light, the refractive index, and the number of levels, the aspect ratio may be 2.1 or more, sometimes exceeding 4, when the pitch is narrow. For example, for a laser beam of 850 nm, the material is quartz, and when designing a rectangular diffusion shape extending at long sides ± 50 ° × short side ± 3.3 ° at 2-level, the original of the diffraction grating is optimum. The maximum aspect ratio exceeds 4 when the depth is 994 nm and the pitch of the narrowest feature is 212 nm.
These designs are performed, for example, using various simulation tools such as GratingMOD (made by Rsoft) using an exact coupled wave analysis (RCWA) algorithm, and Virtuallab (made by LightTrans) using an iterative Fourier transform algorithm (IFTA). be able to. When the light source is not a laser but an LED, it may be designed in consideration of oblique incident light.

It is preferable that the high refractive index convex portion have a portion having an aspect ratio of 2 or more from the viewpoint that infrared rays with a wavelength of 780 nm or more can be shaped into a desired shape.

The cross-sectional shape of the diffraction grating portion may be rectangular as shown in FIGS. 3 to 7B, or may be another shape. 9A to 9D are schematic cross-sectional views showing other embodiments of the cross-sectional shape of the diffraction grating portion. The root 41 of the high refractive index convex portion 2a may be a transparent base material or a base.
In each of the examples shown in FIGS. 9A to 9D, the cross-sectional shape of the high refractive index convex portion is tapered, and therefore, the releasability from the mold at the time of manufacture is excellent.
The thickness of the high refractive index convex portion 2a may increase intermittently from the tip to the root (FIG. 9A), and may continuously increase from the tip to the root (FIG. 9B).
In order to increase the diffraction efficiency of the diffractive optical element, the cross-sectional shape of the diffraction grating portion may be changed from a usual binary (2-level: FIGS. 3 to 7B) to a multistage (4-level (FIG. 9C), 8- It is effective to increase the level (FIG. 9D)). However, if the number of steps of the cross-sectional shape of the diffraction grating portion is excessively increased, the mold making process becomes complicated and the cost is increased. Therefore, in the present disclosure, it is preferable to appropriately select from two values to eight values.
As the number of steps of the cross-sectional shape of the diffraction grating portion is increased, the groove depth becomes deeper. For example, when the refractive index of the cured product of the acrylic resin composition is 1.5, the groove depth at 4-level is 1.5 times the target wavelength, and the groove depth at 8-level Is 1.75 times the target wavelength. The longer the target wavelength, the deeper the required groove depth, and the more difficult the processing.
The minimum machined groove width set at the time of design is usually about 1⁄4 of the target wavelength. In order to increase the efficiency, the minimum machined groove width may be made finer. However, if the minimum machined groove width is too narrow, machining is difficult and time-consuming, so the minimum machined groove width is preferably about 80 to 100 nm.
By forming a high refractive index convex portion using an acrylic resin composition, even in the case where the diffractive optical element of the present disclosure includes an aspect ratio of 2 or more, and further, an aspect ratio of 4 or more, reliability can be obtained. Excellent.

In the diffractive optical element of the present disclosure, the line & space ratio (L / S) is not particularly limited when the high refractive index convex portion is a line (L) and the low refractive index portion is a space (S). The line and space ratio (L / S) is determined by the following equation (A).
Formula (A) (L / S) = l / (l + s)
(In the above formula (A), (L / S) represents a line & space ratio, l represents a line width (nm), and s represents a space width (nm).)
The line and space ratio (L / S) may be appropriately set so as to obtain desired diffracted light, but can be appropriately set, for example, in the range of 0.1 to 0.9. The range of 0.4 to 0.6 is preferable from the point of efficiency.

Further, in the diffractive optical element of the present disclosure, it is preferable that the diffractive optical element have a multistage shape having two or more flat portions in terms of easily increasing the diffraction angle.
The diffractive optical element of the present disclosure can weaken 0th-order light when the aspect ratio is 2 or more, but when the diffraction angle is increased, the 0th-order light from the projection region of the diffracted light can be obtained. It is also possible to obtain diffracted light of a desired shape while removing. This will be described with reference to the drawings. FIG. 10A and FIG. 10B are drawings for explaining the diffractive optical element. 11A is a front view of the screen 22 shown in FIG. 10A, and FIG. 11B is a front view of the screen 22 shown in FIG. 10B.
FIG. 10A is a schematic perspective view showing how the irradiation light 21 is diffracted by the diffractive optical element 10 and a square image 24 is formed at the center of the screen 22. FIG. As shown in FIG. 11A, since the square image 24 includes the zero-order light irradiation position 27, the zero-order light is included in the image 24. When the aspect ratio is 2 or more, the zeroth-order light is suppressed, and therefore, even when the zeroth-order light is included in the image 24, good diffracted light can be obtained.
FIG. 10B is a schematic perspective view showing that the irradiation light 21 is diffracted by the diffractive optical element 10 and a square image 24 is formed on the screen 22. In the example shown in FIG. 10B, the diffraction angles of the first-order lights 26a to 26d are set larger than in the example shown in FIG. 10A. Therefore, as shown in FIG. 11B, the square image 24 does not include the zero-order light irradiation position 27.
As shown in FIG. 10B, by setting the maximum diffraction angle to a large value, it is possible to obtain a diffractive optical element capable of obtaining diffracted light that does not contain zero-order light. From the above points, in the diffractive optical element of the present disclosure, the diffraction grating portion preferably has a multistage shape having two or more flat portions, and further preferably has an aspect ratio of 3.5 or more.

The transparent substrate used in the present disclosure can be appropriately selected and used according to the application from among known transparent substrates. Specific examples of the material used for the transparent substrate include, for example, acetyl cellulose resins such as triacetyl cellulose, polyester resins such as polyethylene terephthalate and polyethylene naphthalate, olefin resins such as polyethylene and polymethylpentene, and acrylic resins Transparent resin such as resin, polyurethane resin, polyether sulfone and polycarbonate, polysulfone, polyimide, polyether, polyether ketone, acronitrile, methacrylonitrile, cycloolefin polymer, cycloolefin copolymer, soda glass, potash glass, Glass such as lead glass, ceramics such as PLZT, quartz, transparent inorganic materials such as fluorite, etc. may be mentioned. Although the birefringence of the transparent substrate does not affect the effect itself of the diffractive optical element, it has an appropriate birefringence when the phase difference of the light incident on the diffractive optical element and the diffused light is an issue. The base material may be selected.
The term "transparent" as used herein refers to a state in which the other side can be seen through visually, but if light of the target wavelength designed by the diffractive optical element can be transmitted, it is practically problematic even if it is colored visually There is no. Moreover, when irradiating an active energy ray from a transparent base material side and hardening an acrylic resin composition, the thing which cuts an active energy ray to irradiate as much as possible of a transparent base material is preferable.
The thickness of the transparent substrate can be appropriately set according to the application of the present disclosure, and is not particularly limited, but is usually 5 to 5,000 μm, and the transparent substrate is supplied in the form of a roll However, it may be one that does not bend enough to be wound, but that bends under load or does not bend completely.
The configuration of the transparent substrate used in the present disclosure is not limited to the configuration composed of a single layer, and may have a configuration in which a plurality of layers are laminated. When a plurality of layers are stacked, layers of the same composition may be stacked, or a plurality of layers having different compositions may be stacked.
Moreover, you may perform surface treatment for improving adhesiveness with an acrylic resin composition, and a primer layer formation to a transparent base material. As surface treatment, general adhesion improvement treatment such as corona treatment and atmospheric pressure plasma treatment can be applied. The primer layer preferably has adhesiveness to both the transparent substrate and the resin composition, and transmits light of the target wavelength. However, depending on the application, by intentionally keeping the adhesion between the transparent substrate and the resin composition low, it is possible to use it by peeling off the diffraction grating portion after shaping from the transparent substrate. Such use is particularly effective when it is desired to reduce the thickness of the diffractive optical element.

(3) Other Configurations of Diffractive Optical Element In addition, the diffractive optical element of the present disclosure has the above-mentioned diffraction grating part on a transparent base material from the viewpoint of preventing damage and the like of the diffraction grating part and having excellent mechanical strength. It may be the composition which has a covering layer in this order (Drawing 5A and Drawing 5B). Although it does not specifically limit as a coating layer, It is preferable to use the thing similar to the said transparent base material. Moreover, when providing a coating layer on a diffraction grating part, you may provide an adhesive (adhesive agent) layer between a diffraction grating part and a coating layer. The pressure-sensitive adhesive or adhesive for the pressure-sensitive adhesive layer (adhesive layer) may be appropriately selected from conventionally known ones, such as a pressure-sensitive adhesive (pressure-sensitive adhesive), a two-component curable adhesive, an ultraviolet curable adhesive, A thermosetting adhesive, a heat melting adhesive, etc. can be suitably used in any bonding form, but when the low refractive index portion is air, an adhesive or adhesive having low flowability should be used. Is preferred. In the case where a part of the low refractive index portion is filled with the adhesive or the adhesive, the diffraction grating portion may be designed in consideration of the amount. In addition, by providing such a covering layer, the secondary effect that it is possible to prevent the reverse engineering which used the unevenness | corrugation of the diffraction grating part as a type | mold can also be anticipated.
Furthermore, by forming the covering layer, it is possible to prevent foreign matter from entering the diffraction grating portion, and it is possible to improve the long-term reliability of the diffractive optical element and the illumination device.

Furthermore, an anti-reflection layer may be further provided on the surface of the transparent base material or the surface of the covering layer opposite to the diffraction grating portion (FIGS. 7A and 7B). The antireflection layer may be appropriately selected from conventionally known ones. For example, it may be a refractive index layer consisting of a low refractive index layer or a single layer of a high refractive index layer, and the low refractive index layer and high refractive index It may be a multilayer film in which layers with a rate layer are sequentially laminated, or it may be an antireflection layer in which a fine concavo-convex shape is formed. By providing the antireflection layer, it is possible to improve the diffraction efficiency of the diffractive optical element.

Moreover, the said transparent base material, the said coating layer, the said adhesion layer (adhesion layer) may contain the conventionally well-known additive in the range which does not impair the effect of this indication. Examples of such additives include ultraviolet light absorbers, infrared light absorbers, light stabilizers, and antioxidants.
The diffractive optical element of the present disclosure may be a transmissive diffractive optical element or a reflective diffractive optical element. Among these, the diffractive optical element of the present disclosure is preferably a transmissive diffractive optical element. In the transmission type diffractive optical element, the aspect ratio of the high refractive index convex portion in the diffraction grating portion needs to be set larger than that of the reflection type diffractive optical element, and as a result, the problem of sticking tends to occur easily. Therefore, a transmissive diffractive optical element having a high refractive index convex portion satisfying the storage elastic modulus (E ′) under the moist heat conditions described above has a higher refractive index convex portion than a reflective diffractive optical element having a similar high refractive index convex portion. Highly effective in preventing sticking.

2. Method of Manufacturing Diffractive Optical Element In the method of manufacturing of the present disclosure, at least one surface side of a transparent substrate, one or more high refractive index convex portions protruding from the surface of the transparent substrate, and one or more low refractive index portions It is a manufacturing method of a diffractive optical element provided with the diffraction grating part which arranges, and shapes light from a light source,
Preparing a mold having a cavity shape for forming the high refractive index convex portion and the low refractive index portion (hereinafter referred to as a mold preparing step);
A cured product sample obtained by irradiating an acrylic resin composition to a cavity of the mold, and curing the acrylic resin composition with ultraviolet light so that the integrated light amount is 1,000 mJ / cm ² . A step of filling an acrylic resin composition having a storage elastic modulus (E ′) at 60 ° C. and a relative humidity of 95% of 0.90 × 10 ⁹ Pa or more and 2.6 × 10 ⁹ Pa or less (hereinafter, acrylic resin Composition filling process),
A step of curing the acrylic resin composition by contacting the transparent substrate and the acrylic resin composition on the side of the cavity opening of the mold and irradiating the active energy ray (hereinafter, acrylic) And a diffraction grating portion having a high refractive index convex portion formed of a cured product of an acrylic resin composition on a transparent substrate by pulling the mold away from the transparent substrate. A process of forming a mold (hereinafter referred to as a mold release process),
It is characterized by having.

12A to 12E are process diagrams schematically showing an example of a method of manufacturing a diffractive optical element.
First, as shown in FIG. 12A, a mold 31 having a cavity shape corresponding to the surface structure of a target diffraction grating portion is prepared (mold preparation step).
Next, as shown in FIGS. 12B and 12C, the acrylic resin composition 32 is filled in the cavity 31a of the mold (acrylic resin composition filling step). Here, the acrylic resin composition 32 is the same composition as the acrylic resin composition described in the above “1. Diffractive optical element”. The filling method is not particularly limited, and a conventionally known method may be appropriately selected. For example, as shown in FIGS. 12B and 12C, the acrylic resin composition 32 may be filled in the cavity 31a by applying the acrylic resin composition 32 to the surface of the mold 31. As a more specific example, first, the acrylic resin composition 32 is placed on the surface of the mold 31 (FIG. 12B), and the transparent substrate 33 is placed thereon. Next, the acrylic resin composition 32 is uniformly spread on the surface of the mold 31 over the transparent base material 33 by the pressure roller 34 (FIG. 12C), and the acrylic resin composition 32 is placed in the cavity 31a. To fill. As shown in FIGS. 12C and 12D, a part of the acrylic resin composition 32 may protrude from the cavity 31a of the mold. The protruding portion of the acrylic resin composition 32 becomes a base after curing. Alternatively, all of the acrylic resin composition 32 may be filled in the mold cavity 31a.
Subsequently, as shown in FIG. 12D, the coating film of the acrylic resin composition 32 is irradiated with active energy rays from the side of the cavity opening of the mold (35) to cure the acrylic resin composition 32. (Acrylic resin composition curing step). The contact between the transparent substrate and the acrylic resin composition may be performed at the same time as the filling of the acrylic resin composition, or may be performed later than the filling of the acrylic resin composition.
Thereafter, as shown in FIG. 12E, the obtained cured product 36 is released from the mold 31 to obtain a diffractive optical element (releasing step).
Hereinafter, the detail of each process of the said manufacturing method is demonstrated. The description similar to that of the diffractive optical element of the present disclosure will be omitted.

(1) Mold Preparation Process A mold for manufacturing a diffractive optical element can be processed by techniques such as laser lithography, electron beam lithography, FIB (Focused Ion Beam), etc., but electron beam lithography is usually suitably used. .
The material may be any material that can be processed at a high aspect ratio, but usually quartz or Si is used. Moreover, it is also possible to use a copy mold (soft mold) replicated by resin from these molds or a copy mold replicated by Ni electroforming.
In addition, the mold surface can be subjected to a release treatment, if necessary. A fluorine-based or silicon-based mold release agent, diamond like carbon, Ni plating, etc. can be applied. The processing method can be appropriately selected from vapor phase processing such as vapor deposition or sputtering, ALD (Atomic Layer Deposition) or the like, and liquid phase processing such as coating or dipping or plating.
Since the shape required for the diffractive optical element is usually as small as several mm square to several cm square, the efficiency of replication can be increased by arranging and processing the shapes of a plurality of diffraction grating parts in one mold. When emphasis is placed on throughput, the above-mentioned molds or copy molds may be arranged side by side and replicated to be used as a multi-faced mold.

When volume change at the time of hardening of an acrylic resin composition becomes a problem, it can also be corrected and mold design can be performed. Further, in consideration of ease of mold release, the opening on the opening side may be wider than the back of the fine structure of the mold (FIGS. 9A to 9D). In this case, the surface of the diffraction grating portion of the obtained diffractive optical element becomes thin.
Further, the diffractive optical element of the present disclosure generally includes a plurality of grooves having different pitches (openings) with respect to one diffractive optical element, since there are a plurality of regions with different periodic structures. When forming a mold, the depth in dry etching tends to vary depending on the pitch (opening). However, since such variations lead to a reduction in efficiency, it is important to optimize the machining process and keep it within ± 10% of the desired depth.
When forming a high refractive index convex portion having an aspect ratio of 2 or more, the height unevenness of the high refractive index convex portion tends to easily occur. In such a case, by aiming the depth of the mold slightly deeper than the design value, it is easy to obtain a diffractive optical element having desired optical characteristics while having height variations.

(2) Acrylic resin composition filling step "A cured product sample obtained by irradiating and curing ultraviolet light so that the integrated light amount is 1,000 mJ / cm ² to the acrylic resin composition" means the diffraction obtained It simulates the cured product of the acrylic resin composition that will actually be contained in the diffraction grating portion of the optical element. Thus, using the acrylic resin composition whose storage elastic modulus (E ') at 60 ° C. and 95% relative humidity in the cured product sample is 0.90 × 10 ⁹ Pa or more and 2.6 × 10 ⁹ Pa or less As a result, it is possible to obtain a diffractive optical element that can prevent sticking under moist heat conditions and can reduce pattern peeling at the time of mold release. The reason is as described above in “1. Diffractive optical element”.
Although the above-mentioned example was what forms the coating film of an acrylic resin composition in the metal mold | die side, you may form a coating film in the transparent base material side. As a method of forming a coating film, in addition to the examples described above, a suitable coating method can be selected from conventionally known coating methods such as die coating, bar coating, gravure coating, and spin coating.
As the transparent substrate, those described in the above "1. Diffractive optical element" can be used. The transparent substrate may be a sheet-like one, or a long one may be used to sequentially perform the coating step, the acrylic resin composition curing step, and the release step by a roll-to-roll method. In the case where the mold is a hard material that is hard to bend, it is preferable that the transparent substrate be flexible so as to resist bubbles. Conversely, when using a hard transparent substrate, it is preferable to use a soft mold as the mold.

(3) Acrylic resin composition curing step A step of contacting the transparent substrate with the acrylic resin composition (hereinafter referred to as a contacting step) and a step of irradiating the acrylic resin composition with an active energy ray (hereinafter referred to as The irradiation step may be performed simultaneously, or the contact step may be performed prior to the irradiation step.
The irradiation of ultraviolet light or electron beam may be performed at one time or divided into multiple times, and when divided into multiple times, additional irradiation may be performed after curing to some extent and releasing.

(4) Releasing Step As described above, since the specific acrylic resin composition is used in the manufacturing method of the present disclosure, it is possible to reduce the amount of pattern cracking when the mold is separated from the transparent substrate. Particularly, in the diffractive optical element to be obtained, when the aspect ratio of the high refractive index convex portion is 2 or more, in the past, pattern peeling was likely to occur during mold release, but according to the manufacturing method of the present disclosure, such pattern It is possible to reduce the number of baldness.

(5) Other Steps In the case of further manufacturing an illumination device using the obtained diffractive optical element, it is conceivable to carry out, for example, the following steps. However, the method of manufacturing the lighting device is not limited to the method described below.
The following description is based on the reference numerals shown in FIG. First, the frame 11 provided with the conduction part 11a and the internal space 11c is prepared. The frame 11 may be a combination of two or more members (for example, a combination of a flat substrate and a hollow cylinder). Next, the light source 12 is placed in the internal space 11c of the frame 11, and the light source 12 and the conducting part 11a are electrically connected using the lead 13 and the like. Subsequently, the diffractive optical element 10 is mounted on the frame 11. By mounting the structure obtained in this manner on the mounting substrate 14, a temporary assembly can be obtained. At this time, alignment is performed such that the position of the solder ball placed on the mounting substrate 14 overlaps the position of the conductive portion 11 a of the frame 11.
The temporary assembly is placed in a reflow furnace and heated at a temperature of 260 to 280 ° C. for 0.5 to 1.5 minutes to solder the mounting substrate 14 and the frame 11 to obtain the lighting device 20. Be

3. Acrylic Resin Composition The acrylic resin composition of the present disclosure comprises, on at least one side of a transparent substrate, one or more high refractive index protrusions projecting from the surface of the transparent substrate, and one or more low refractive indexes An acrylic resin composition for forming a high refractive index convex portion of a diffractive optical element having a diffraction grating portion in which the light from the light source is shaped, wherein the integration is performed with respect to the acrylic resin composition The storage elastic modulus (E ') at 60 ° C. and 95% relative humidity of a cured product sample obtained by curing by irradiation with ultraviolet light so that the amount of light is 1,000 mJ / cm ² is 0.90 × 10 ⁹ Pa or more It is characterized in that it is 2.6 × 10 ⁹ Pa or less.

The acrylic resin composition preferably contains an active energy ray curable component, and the above physical properties can be obtained after curing. Moreover, if light of the designed target wavelength can be transmitted, there is no practical problem even if it is visually colored after curing.
The details of the acrylic resin composition of the present disclosure are as described in “(1) Cured product of acrylic resin composition” in “1. Diffractive optical element” described above.
Further, the method of forming the high refractive index convex portion using the acrylic resin composition of the present disclosure is as described in the above-mentioned “2. Method of manufacturing a diffractive optical element”.

When the acrylic resin composition for forming the high refractive index convex portion is filled in the mold, if the fluidity is too low, it is difficult to enter into the fine groove, and if it is too high, the composition spreads thinly, and the predetermined It may not be possible to secure the thickness. In the case of roll forming, too high fluidity causes ink drop. In the present disclosure, an acrylic resin is preferable such that the viscosity at 25 ° C. of the acrylic resin composition is about several tens of mPas to several thousands of mPas. Since viscosity changes also with temperature, when forming a high refractive index convex part using the acrylic resin composition of this indication, it is preferable to perform suitable temperature control suitably.

4. Lighting Device (1) Configuration of Lighting Device A lighting device according to the present disclosure includes a frame having a conductive portion capable of supplying power from the outside and an opening serving as a light exit surface, a light source, and the above-described diffractive optical element The light source is fixed in an internal space of the body and connected to the conductive portion, and the diffractive optical element is disposed in the opening.
According to the illumination device of the present disclosure, light shaped into a desired shape can be emitted.

A lighting device of the present disclosure will be described with reference to the drawings. FIG. 13 is a cross-sectional view schematically showing an embodiment of a light irradiation apparatus according to the present disclosure. The illumination device 20 shown in the example of FIG. 13 includes a frame 11, a light source 12, and the above-described diffractive optical element 10. The frame 11 has a conducting portion 11 a which can be supplied with power from the outside, and an opening 11 b which is a light emitting surface. As shown in FIG. 13, the frame 11 further includes an internal space 11 c, and the light source 12 is fixed to the internal space 11 c. Furthermore, the light source 12 is connected to the conducting part 11a. The light source 12 may be connected in direct contact with the conducting portion 11a, or may be connected to the conducting portion 11a via the conducting wire 13 as shown in FIG. Then, the diffractive optical element 10 is disposed in the opening 11 b.
The frame 11 may be a combination of two or more members. For example, the frame 11 may be a combination of a flat substrate (base portion) for light source control and a hollow cylinder placed thereon.
By mounting the frame 11 on the mounting substrate 14 (motherboard) and connecting the light source 12 to the electric circuit of the mounting substrate 14, the light source 12 can be interlocked with other devices on the mounting substrate 14.

In the illumination device of the present disclosure, the light source is not particularly limited, and a known light source can be used. Since the diffractive optical element according to the present disclosure is designed for the purpose of diffraction of a specific wavelength, it is preferable to use a laser light source having a high intensity of the specific wavelength, an LED (light emitting diode) light source or the like as a light source. In the present disclosure, any light source such as a directional laser light source or a diffusive LED (light emitting diode) light source can be suitably used. In the present disclosure, it is preferable that the light source be appropriately selected from among reproducible light sources to be simulated in designing the diffractive optical element according to the present disclosure. Among them, in the case of using a diffractive optical element that diffracts an infrared ray having a wavelength of 780 nm or more, it is preferable to select a light source capable of emitting an infrared ray having a wavelength of 780 nm or more.

The illumination device of the present disclosure may include at least one diffraction grating according to the present disclosure, and may further include other optical elements as needed. Other optical elements include, for example, a polarizing plate, a lens, a prism, and a pass filter that transmits a target wavelength of a specific wavelength, particularly a diffractive optical element. When using it combining a several optical element, it is preferable to bond optical elements together from the point which suppresses interface reflection.

(2) Use of lighting device The lighting device according to the present disclosure can emit light shaped into a desired shape, and is preferably used as a lighting device for a sensor from the viewpoint that infrared rays can be used. Can. For example, infrared illumination for nighttime, illumination for security sensor, illumination for human detection sensor, illumination for collision prevention sensor for unmanned aerial vehicles and automobiles, illumination for personal identification device, illumination for inspection device, from the point that light can be effectively shaped , Etc., and simplification, downsizing and power saving of the light source become possible.

Hereinafter, the present disclosure will be specifically described with reference to examples. These descriptions do not limit the present disclosure.

1. Production of Optical Diffraction Grating [Examples 1 to 9, Comparative Examples 1 to 4]
(Diffraction grating design)
The shape design was performed under the following conditions using a simulation tool.
Target light source: Laser light of wavelength 980 nm Material refractive index: 1.456
Diffusion shape: A rectangular area that spreads to the long side ± 50 ° × short side ± 3.3 ° Area size: 5 mm square Diffraction grating level: 2-level (binary)
The optimum depth of the obtained diffraction grating shape was 1087 nm, the pitch of the narrowest shape was 250 nm, and the maximum aspect ratio was 4.35.

(Molding)
Using a 6-inch square synthetic quartz plate, a designed shape of quartz DOE was produced by an electron beam lithography process using an electron beam drawing apparatus and a dry etching apparatus.
In SEM observation, it could be confirmed that it had finished to a predetermined size, and when a laser of 980 nm was made incident and the diffracted light was projected on a screen and observed with an infrared camera, it could be confirmed that it had spread into a predetermined rectangular shape. .

(Preparation of acrylic resin composition)
The acrylic resin composition 1 to 13 is prepared by blending the (meth) acrylate compound (tetra- or higher functional (meth) acrylate, bifunctional (meth) acrylate) shown in Table 1 below and the photopolymerization initiator in the amounts shown in Table 1 Was prepared. In addition, the numerical value regarding these compounds in Table 1 shows a mass part, and the total amount of a (meth) acrylate compound will be 100 mass parts.

(Resin molding method)
Resin molding of the diffraction grating portion was performed as follows.
First, using the above-mentioned quartz DOE as a mold, any one of acrylic resin compositions 1 to 11 and 13 was dropped on the diffractive surface. Next, a PET film (Toyobo Co., Ltd., A4300, 100 μm thick) as a transparent substrate was laminated from above with a roller, and the acrylic resin composition was spread uniformly. Furthermore, after irradiating an ultraviolet-ray from the transparent base material side so that an accumulated light quantity may be 1,000 mJ / cm < ² > in that state, and hardening the said acrylic resin composition, a transparent base material and a shaping layer are mold-formed. Peeling was performed to obtain a diffractive optical element (Examples 1 to 9, Comparative Examples 1, 2 and 4). In addition, since the viscosity of the acrylic resin composition 12 was high and the composition 12 could not be filled in the cavity of the mold, the cured product could not be shaped, and a diffractive optical element could not be obtained (Comparative Example 3).
The diffraction grating portion of the obtained diffractive optical element has the following periodic structure 1. The periodic structure 1 has about 20 high refractive index convex portions. Each high refractive index convex portion has a linear shape in a plan view, a rectangular cross section, and a constant height (H). However, the widths (W) of the respective high refractive index convex portions are formed to be different from one another within the following range.
[Periodic structure 1]
High refractive index convex part height (H): 500 nm
Width (W) of high refractive index convex part: fixed width in the range of 50 nm to 500 nm

2. Production of Lighting Device and Evaluation of Reflow Resistance A lighting device was produced using the diffractive optical elements of Example 6 and Comparative Example 2 described above.
The following description is based on the reference numerals shown in FIG. First, the light source 12 was placed in the internal space 11 c of the frame 11, and the light source 12 and the conductive portion 11 a were electrically connected using the conducting wire 13. Next, the diffractive optical element of Example 6 or Comparative Example 2 was placed on the frame 11. By placing the structure obtained in this manner on the mounting substrate 14, a temporary assembly was obtained. At this time, alignment was performed so that the position of the solder ball placed on the mounting substrate 14 overlapped with the position of the conductive portion 11 a of the frame 11.
The temporary assembly was placed in a reflow furnace, heated under a temperature condition of 260 ° C. for 1.5 minutes, and the mounting substrate 14 and the frame 11 were soldered to manufacture the lighting device of Example 6 or Comparative Example 2. .

About the diffractive optical element contained in the illuminating device of Example 6 and Comparative Example 2, the mass change rate and the transmittance | permeability fluctuation | variation before and behind reflow were investigated by the following method, respectively.
(Calculation method of mass change rate of diffractive optical element)
The mass of the diffractive optical element before and after the reflow was measured, and the mass change rate a was calculated from the following formula I.
Formula I a = {(M ₀ -M ₁ ) / M ₀ } × 100
(In the above formula I, a represents a mass change rate (%), M ₀ represents a mass of the diffractive optical element before reflow (mg), and M ₁ represents a mass of the diffractive optical element after reflow (mg).)
The allowable range of mass change rate is 2.0% or less.
(Method of calculating transmittance fluctuation of diffractive optical element)
The transmittance (%) of the diffractive optical element before and after the reflow was measured. The transmittance was measured using an ultraviolet visible near infrared (UV-Vis-NIR) spectrophotometer (UV-3150 manufactured by Shimadzu Corporation). The transmittance of the transparent substrate and the diffraction grating portion of the diffractive optical element having a wavelength of 850 nm was measured from this device.
The absolute value of the difference between the transmittance of the diffractive optical element before reflow and the transmittance of the diffractive optical element after reflow was taken as the transmittance fluctuation (%) of the diffractive optical element.
The allowable range of the transmittance fluctuation is 1.0% or less.

Regarding the diffractive optical element included in the illumination device of Comparative Example 2, the mass change rate before and after reflow for the reflow at 260 ° C. for 1.5 minutes is 3.8%, and the transmittance fluctuation before and after the reflow is 0.0% It is. Therefore, this result is beyond the allowable range of the mass change rate. The reason is that, since the compound used for the diffractive optical element of Comparative Example 2 is a bifunctional acrylic resin, this bifunctional acrylic resin is instantaneously exposed to a high temperature environment of 260 ° C. As a result of sublimation, it is conceivable that the fine structure of the diffraction grating portion changes.
On the other hand, for the diffractive optical element included in the illumination device of Example 6, the mass change rate before and after reflow for the reflow at 260 ° C. for 1.5 minutes is 1.5%, and the transmittance change before and after the reflow is It is 0.1%. All these results are within the acceptable range. The reason is that the acrylic resin composition used for the diffractive optical element of Example 6 is exposed to a high temperature environment of 260 ° C. instantaneously because it contains a large amount of highly heat resistant tetrafunctional or higher urethane acrylate. Even in this case, mass fluctuation hardly occurs, and as a result, it is considered that the change in the fine structure of the diffraction grating portion can be minimized.

3. Measurement of Viscoelasticity of Cured Product of Acrylic Resin Composition Acrylic resin compositions 1 to 13 are irradiated with ultraviolet light and cured so that the integrated light amount is 1,000 mJ / cm ² , and the substrate and the uneven shape A test single film having a thickness of 0.1 mm, a width of 5 mm and a length of 15 mm was obtained.
Next, storage at 60 ° C. and 95% relative humidity by measuring the dynamic viscoelasticity based on JIS K 7244 and conditions of measurement temperature 60 ° C. and relative humidity 95% and measurement conditions shown in Table A below. The elastic modulus E ′ and the loss elastic modulus E ′ ′ were determined, and tan δ was calculated from the results of the E ′ and E ′ ′. The measurement apparatus used Rheogel E4000 made from UBM. The storage modulus E ′ (60 ° C., 95%) and tan δ (60 ° C., 95%) are shown in Table 1.
Furthermore, by measuring the dynamic viscoelasticity based on the conditions of a measurement temperature of 30 ° C. and a relative humidity of 30% and the measurement conditions shown in Table A below, using the same test single film, in accordance with JIS K7244. The storage elastic modulus E ′ was determined at 30 ° C. and 30% relative humidity. Each value of storage elastic modulus E ′ (30 ° C., 30%) is shown in Table 1.

4. Measurement of recovery rate of cured product of acrylic resin composition As in the case of "3. Measurement of visco-elasticity of cured product of acrylic resin composition" described above, test single films for acrylic resin compositions 1 to 13 were prepared. did.
According to JIS Z 2244 (2003), a Vickers hardness test was carried out under the following measurement conditions. Specifically, an indenter was pressed into the surface of each test single membrane under the following measurement conditions, and the recovery rate (%) of the surface of the test single membrane was measured. As a measuring apparatus, PICDENTER HM-500 manufactured by Fisher Instruments was used. The results are shown in Table 1.
<Measurement conditions>
・ Maximum load 0.2mN
・ Loading speed 0.2 mN / 10 sec ・ Holding time 5 seconds ・ Load unloading speed 0.2 mN / 10 sec ・ Indenter Vickers indenter ・ Measuring temperature 25 ° C

5. Measurement of Glass Transition Temperature (Tg) of Acrylic Resin Composition With respect to acrylic resin compositions 1 to 13, ultraviolet rays are irradiated and cured so that the integrated light amount is 1,000 mJ / cm ² , and the substrate and the unevenness are obtained. Test single films each having a thickness of 0.1 mm, a width of 5 mm, and a length of 20 mm were obtained without any shape.
Using a dynamic viscoelasticity tester (DMS6100 manufactured by Seiko Instruments Inc.), apply a periodic external force at a frequency of 10 Hz in the length direction of each test piece, and measure in the range of -20 ° C to 200 ° C. Each storage elastic modulus E ′ and loss elastic modulus E ′ ′ were determined. From the results of E ′ and E ′ ′, tan δ = E ′ ′ / E ′ was calculated. It was set as the glass transition temperature Tg (degreeC) of a system resin composition.

6. Sticking Evaluation and Pattern Molar Evaluation The diffractive optical elements of Examples 1 to 9 and Comparative Examples 1, 2 and 4 were observed by SEM. In addition, since the diffractive optical element was not obtained as Comparative Example 3 (using the acrylic resin composition 12) as described above, the following evaluation was not performed.
The sticking evaluation was performed as follows. First, for the periodic structure 1 (height H = 500 nm), among the high refractive index convex portions in which sticking did not occur, the high refractive index convex portion having the smallest width was specified. Then, the width of the high refractive index convex portion is taken as the minimum width W ¹ _min (nm) in the sticking evaluation, and the value obtained by dividing the height H (500 nm) by the minimum width W ¹ _min in the sticking evaluation The maximum aspect ratio was used. As the minimum width W ¹ _min is smaller and the maximum aspect ratio is larger, it can be said that the cured product forming the high refractive index convex portion has an appropriate hardness, so that sticking is less likely to occur.
Pattern haze evaluation was performed as follows. First, for the periodic structure 1, among the high refractive index convex portions in which no pattern burrs were generated, the high refractive index convex portion having the smallest width was specified. Then, the width of the high refractive index convex portion, and a minimum width ^W ₂ min (nm) in the pattern Moge evaluation. After that, the maximum aspect ratio was calculated in the same manner as the above-mentioned sticking evaluation. As the minimum width W ² _min is smaller and the maximum aspect ratio is larger, it can be said that the cured product forming the high refractive index convex portion has appropriate flexibility, so that the pattern is less likely to occur.

7. Discussion Table 1 below summarizes the compositions, physical property values, and evaluation results of the acrylic resin compositions used in Examples 1 to 9 and Comparative Examples 1 to 4.
In Table 1 below, “> 500” for the maximum width of the sticking evaluation means that sticking occurred for all of the high refractive index convex portions having the width (W) within the range of 50 nm to 500 nm. Do. Therefore, in this case, the aspect ratio is not calculated.
In addition, in Comparative Example 3, no diffractive optical element was obtained as described above, so there is no description of the sticking evaluation result and the pattern evaluation result.

In Table 1, compound (1) is a hexafunctional urethane acrylate (Mw: 1,400) represented by PETA-IPDI-PETA. "PETA" indicates pentaerythritol triacrylate, "IPDI" indicates isophorone diisocyanate, and "-" indicates a urethane bond.

In Table 1, the compound (2) is a 9-functional urethane acrylate (Mw: 11,000) represented by the following formula (i).

(In the above formula (i), “PETA” represents pentaerythritol triacrylate, “HDI” represents hexamethylene diisocyanate, and “-” represents a urethane bond, respectively).

In Table 1, compound (3) is a 10-functional urethane acrylate (Mw: 2,000) represented by DPPA-IPDI-DPPA. "DPPA" indicates dipentaerythritol pentaacrylate, "IPDI" indicates isophorone diisocyanate, and "-" indicates a urethane bond.

In Table 1, the compound (4) is a 15-functional urethane acrylate (Mw: 2,300) represented by the following formula (ii).

(In the above formula (ii), “DPPA” indicates dipentaerythritol pentaacrylate, “HDI” indicates hexamethylene diisocyanate, and “-” indicates a urethane bond, respectively).

In Table 1, the compound (5) is a bifunctional urethane acrylate (Mw: 2,000) represented by caprolactone modified HEA-hydrogenated MDI-caprolactone modified HEA. "HEA" indicates hydroxyethyl acrylate, "MDI" indicates diphenylmethane diisocyanate, and "-" indicates a urethane bond.

In Table 1, the compound (6) is 1,9-nonanediol diacrylate (CAS No. 107481-28-7, Mw: 268).

In Table 1, compound (7) is polyethylene glycol # 600 diacrylate (Mw: 700).

First, Comparative Example 1 will be examined. In Comparative Example 1, an acrylic resin composition 10 having a storage elastic modulus (E ′) at 60 ° C. and a relative humidity of 95% of 0.42 × 10 ⁹ Pa is used in Comparative Example 1.
In Comparative Example 1, the minimum width W ² _min of the high refractive index convex portion in which no pattern burrs are generated is 90 nm, and the maximum aspect ratio is 5.6. Therefore, there is no problem in the flexibility of the high refractive index convex portion.
However, in Comparative Example 1, sticking occurs even if the width W of the high refractive index convex portion is 500 nm. This is considered to be because the storage elastic modulus (E ′) under wet heat conditions is smaller than 0.90 × 10 ⁹ Pa and the high refractive index convex portion is too soft.

Next, Comparative Example 2 will be examined. The acrylic resin composition 11 whose storage elastic modulus (E ') at 60 ° C. and 95% relative humidity of the cured product is 0.06 × 10 ⁹ Pa is used in Comparative Example 2.
In Comparative Example 2, the minimum width W ² _min of the high refractive index convex portion in which no pattern burrs are generated is 85 nm, and the maximum aspect ratio is 5.9. Therefore, there is no problem in the flexibility of the high refractive index convex portion.
However, in Comparative Example 2, the minimum width W ¹ _min of the high refractive index convex portion in which sticking does not occur is as large as 250 nm, and the maximum aspect ratio is as small as 2.0. Therefore, it can be said that the diffractive optical element of Comparative Example 2 is susceptible to sticking. This is formed as a result that the acrylic resin composition 11 does not contain a tetrafunctional or higher functional (meth) acrylate while the storage elastic modulus (E ') under wet heat conditions is smaller than 0.90 × 10 ⁹ Pa. It is considered that the high refractive index convex portion is too soft.

Subsequently, Comparative Example 3 will be examined. In Comparative Example 3, an acrylic resin composition 12 whose storage elastic modulus (E ′) at 60 ° C. and 95% relative humidity of a cured product is 3.10 × 10 ⁹ Pa is used.
As described above, since the acrylic resin composition 12 has a high viscosity and the composition 12 can not be filled in the cavity of the mold, the cured product can not be shaped, and a diffractive optical element can not be obtained. It is considered that this is because, as a result of the storage elastic modulus (E ′) under wet heat conditions being greater than 2.6 × 10 ⁹ Pa, the acrylic resin composition 12 lacks flexibility.

Subsequently, Comparative Example 4 will be examined. In Comparative Example 4, an acrylic resin composition 13 whose storage elastic modulus (E ′) at 60 ° C. and 95% relative humidity of a cured product is 0.18 × 10 ⁹ Pa is used.
In Comparative Example 4, the minimum width W ² _min of the high refractive index convex portion in which no pattern haze occurs is 90 nm, and the maximum aspect ratio is 5.6. Therefore, there is no problem in the flexibility of the high refractive index convex portion.
However, in Comparative Example 4, sticking occurs even if the width W of the high refractive index convex portion is 500 nm. This is considered to be because the storage elastic modulus (E ′) under wet heat conditions is smaller than 0.90 × 10 ⁹ Pa and the high refractive index convex portion is too soft.

As shown in the results of Examples 1 to 9, the storage elastic modulus (E ′) at 60 ° C. and 95% relative humidity after curing is 0.90 × 10 ⁹ Pa or more and 2.6 × 10 ⁹ Pa or less It has become clear that, by using the acrylic resin composition, sticking can be prevented under moist heat conditions, and pattern burrs can be reduced.

From Table 1, the storage elastic modulus (E ') at 60 ° C. after curing and at a relative humidity of 95% is 1.0 × 10 ⁹ Pa or more and 2.0 × 10 ⁹ Pa or less from Examples 1 to 9 Further, in Examples 1 to 2 and 4 to 6 using an acrylic resin composition having a restitution ratio of 60% or more, the highest refractive index convex portion where sticking does not occur as compared with the other examples. It can be seen that the small width W ¹ _min is as small as 120 nm or less, and the maximum aspect ratio is as large as 4.2 or more. This can be said to be due to the fact that sticking is difficult to occur due to having a suitable storage elastic modulus (E ′) under moist heat conditions and a high recovery rate.

1 Transparent Substrate 2 Diffraction Grating Part 2a High Refractive Index Convex Part 2b Low

Refractive Index Part

2A, 2B, 2C, 2D Partial Periodic Structure (Area)
Reference Signs List 3 base 5 coating layer 7 low refractive index resin 9 anti-reflection layer 10 diffractive optical element 11 frame 11 a conductive portion 11 b opening 11 c internal space 12 light source 13 lead 14 mounting substrate 20 illumination device 21 irradiation light 22 screen 23 irradiation irradiation light Region 24 Irradiated region of light passing through diffractive optical element 250 0th-

order light

26a, 26b, 26c, 26d 1st-order light (diffracted light)
27 0th order light irradiation position 31 mold 31a mold cavity 32 acrylic resin composition 33 transparent substrate 34 pressure roller 35 active energy ray irradiation 36 cured film 41 transparent substrate or base 50 diffractive optical element with sticking occurred 51 moisture 101 substrate 102 broken cured product 103 mold

Claims

A diffractive optical element for shaping light from a light source,
A diffraction grating portion in which one or more high refractive index convex portions protruding from the surface of the transparent substrate and one or more low refractive index portions are arranged on at least one surface side of the transparent substrate,
The high refractive index convex portion is
It is formed of a cured product of an acrylic resin composition,
A diffractive optical element, wherein the storage elastic modulus (E ′) at 60 ° C. and 95% relative humidity of the cured product is 0.90 × 10 9 Pa or more and 2.6 × 10 9 Pa or less.
The diffractive optical element according to claim 1, wherein the storage elastic modulus (E ') at 30 ° C and a relative humidity of 30% of the cured product of the acrylic resin composition is 1 × 10 8 Pa or more and 5 × 10 9 Pa or less. element.
The ratio (tan δ (= E ′ ′ / E ′)) of loss elastic modulus (E ′ ′) to storage elastic modulus (E ′) at 60 ° C. and 95% relative humidity of the cured product of the acrylic resin composition is 0. The diffractive optical element according to claim 1, which is 12 or less.
The diffractive optical element according to any one of claims 1 to 3, wherein the acrylic resin composition contains a urethane bond.
The said acrylic resin composition is an active energy ray curable resin composition containing tetrafunctional or more (meth) acrylate and bifunctional (meth) acrylate as described in any one of Claims 1 to 4. Diffractive optical element.
The active energy ray-curable resin composition contains 40% by mass or more and 80% by mass or less of the tetrafunctional or higher functional (meth) acrylate and 10% by mass of the bifunctional (meth) acrylate with respect to all the curable components. The diffractive optical element according to claim 5, wherein the diffractive optical element contains at least 60% by mass.
The diffractive optical element according to claim 5, wherein the tetrafunctional or higher functional (meth) acrylate comprises a tetrafunctional or higher functional urethane (meth) acrylate.
The tetrafunctional or higher urethane (meth) acrylate is a compound in which an isocyanate group of a polyvalent isocyanate compound and a hydroxyl group of a compound having one hydroxyl group and two or more (meth) acrylic groups in the molecule form a urethane bond The diffractive optical element according to claim 7.
The diffractive optical element according to any one of claims 5 to 8, wherein the bifunctional (meth) acrylate has a molecular weight (Mw) of 100 or more and 5,000 or less.
The recovery rate of the cured product of the acrylic resin composition is measured by a Vickers hardness test conducted under measurement conditions of maximum load 0.2 mN and holding time 10 seconds in accordance with JIS Z 2244 (2003). The diffractive optical element according to any one of claims 1 to 9, which is 60% or more.
The diffractive optical element according to any one of claims 1 to 10, wherein the high refractive index convex portion has a portion having a height of 400 nm or more.
The top of the high refractive index convex portion is defined as the upper end, and the position of the valley bottom between the high refractive index convex portion and another high refractive index convex portion adjacent thereto, or the highest from the top of the high refractive index convex portion When the lower end of the high-refractive-index convex portion is defined as the lower end of the near flat portions, the height corresponding to half the height difference between the upper end and the lower end from the lower end to the upper end of the high-refractive-index convex portion When the ratio of the height of the high refractive index convex portion to the width of the high refractive index convex portion at the position of is defined as the aspect ratio of the high refractive index convex portion,
The diffractive optical element according to any one of claims 1 to 11, wherein an aspect ratio of the high refractive index convex portion is 2 or more.
A light from a light source is provided with a diffraction grating portion in which one or more high refractive index convex portions protruding from the surface of the transparent base and one or more low refractive index portions are arranged on at least one surface side of the transparent base A method of manufacturing a diffractive optical element for shaping
Preparing a mold having a cavity shape for forming the high refractive index convex portion and the low refractive index portion;
A cured product sample obtained by irradiating an acrylic resin composition to a cavity of the mold, and curing the acrylic resin composition with ultraviolet light so that the integrated light amount is 1,000 mJ / cm 2 . Filling an acrylic resin composition having a storage elastic modulus (E ′) at 60 ° C. and a relative humidity of 95% of 0.90 × 10 9 Pa or more and 2.6 × 10 9 Pa or less,
A step of curing the acrylic resin composition by bringing the transparent substrate and the acrylic resin composition into contact with each other on the side of the cavity opening of the mold and irradiating active energy rays; Forming a diffraction grating portion having a high refractive index convex portion formed of a cured product of an acrylic resin composition on a transparent substrate by pulling the mold away from the substrate;
A method of manufacturing a diffractive optical element, comprising:
The manufacturing method according to claim 13, wherein a storage elastic modulus (E ') at 30 ° C and a relative humidity of 30% of a cured product of the acrylic resin composition is 1 × 10 8 Pa or more and 5 × 10 9 Pa or less. .
The ratio (tan δ (= E ′ ′ / E ′)) of loss elastic modulus (E ′ ′) to storage elastic modulus (E ′) at 60 ° C. and 95% relative humidity of the cured product of the acrylic resin composition is 0. The production method according to claim 13 or 14, which is 12 or less.
The production method according to any one of claims 13 to 15, wherein the acrylic resin composition contains a urethane bond.
The said acrylic resin composition is an active energy ray curable resin composition containing tetrafunctional or more (meth) acrylate and bifunctional (meth) acrylate as described in any one of Claims 13 to 16. Manufacturing method.
The active energy ray-curable resin composition contains 40% by mass or more and 80% by mass or less of the tetrafunctional or higher functional (meth) acrylate and 10% by mass of the bifunctional (meth) acrylate with respect to all the curable components. The production method according to claim 17, wherein the content is from 60% by mass to 60% by mass.
The manufacturing method according to claim 17 or 18, wherein the tetrafunctional or higher functional (meth) acrylate comprises a tetrafunctional or higher functional urethane (meth) acrylate.
The tetrafunctional or higher urethane (meth) acrylate is a compound in which an isocyanate group of a polyvalent isocyanate compound and a hydroxyl group of a compound having one hydroxyl group and two or more (meth) acrylic groups in the molecule form a urethane bond 20. The method of claim 19, wherein
21. The method according to any one of claims 17 to 20, wherein the bifunctional (meth) acrylate has a molecular weight (Mw) of 100 or more and 5,000 or less.
The recovery rate of the cured product of the acrylic resin composition is measured by a Vickers hardness test conducted under measurement conditions of maximum load 0.2 mN and holding time 10 seconds in accordance with JIS Z 2244 (2003). The method according to any one of claims 13 to 21, which is 60% or more.
The manufacturing method according to any one of claims 13 to 22, wherein the high refractive index convex portion has a portion having a height of 400 nm or more.
The top of the high refractive index convex portion is defined as the upper end, and the position of the valley bottom between the high refractive index convex portion and another high refractive index convex portion adjacent thereto, or the highest from the top of the high refractive index convex portion When the lower end of the high-refractive-index convex portion is defined as the lower end of the near flat portions, the height corresponding to half the height difference between the upper end and the lower end from the lower end to the upper end of the high-refractive-index convex portion When the ratio of the height of the high refractive index convex portion to the width of the high refractive index convex portion at the position of is defined as the aspect ratio of the high refractive index convex portion,
The method according to any one of claims 13 to 23, wherein an aspect ratio of the high refractive index convex portion is 2 or more.
A light from a light source is provided with a diffraction grating portion in which one or more high refractive index convex portions protruding from the surface of the transparent base and one or more low refractive index portions are arranged on at least one surface side of the transparent base An acrylic resin composition for forming a high refractive index convex portion of a diffractive optical element for shaping
The storage elastic modulus (E ′) at 60 ° C. and 95% relative humidity of a cured product sample obtained by irradiating and curing ultraviolet light so that the integrated light amount is 1,000 mJ / cm 2 with respect to the acrylic resin composition is And an acrylic resin composition which is 0.90 × 10 9 Pa or more and 2.6 × 10 9 Pa or less.
The acrylic resin according to claim 25, wherein a storage elastic modulus (E ') at 30 ° C and a relative humidity of 30% of a cured product of the acrylic resin composition is 1 × 10 8 Pa or more and 5 × 10 9 Pa or less. Resin composition.
The ratio (tan δ (= E ′ ′ / E ′)) of loss elastic modulus (E ′ ′) to storage elastic modulus (E ′) at 60 ° C. and 95% relative humidity of the cured product of the acrylic resin composition is 0. The acrylic resin composition according to claim 25 or 26, which is 12 or less.
The acrylic resin composition according to any one of claims 25 to 27, wherein the acrylic resin composition contains a urethane bond.
The said acrylic resin composition is an active energy ray curable resin composition according to any one of claims 25 to 28, which is a tetrafunctional or higher functional (meth) acrylate and a bifunctional (meth) acrylate. Acrylic resin composition.
The active energy ray-curable resin composition contains 40% by mass or more and 80% by mass or less of the tetrafunctional or higher functional (meth) acrylate and 10% by mass of the bifunctional (meth) acrylate with respect to all the curable components. 30. The acrylic resin composition according to claim 29, which contains at least 60% by mass.
The acrylic resin composition according to claim 29 or 30, wherein the tetrafunctional or higher functional (meth) acrylate comprises a tetrafunctional or higher functional urethane (meth) acrylate.
The tetrafunctional or higher urethane (meth) acrylate is a compound in which an isocyanate group of a polyvalent isocyanate compound and a hydroxyl group of a compound having one hydroxyl group and two or more (meth) acrylic groups in the molecule form a urethane bond The acrylic resin composition according to claim 31.
The acrylic resin composition according to any one of claims 29 to 32, wherein the bifunctional (meth) acrylate has a molecular weight (Mw) of 100 or more and 5,000 or less.
The recovery rate of the cured product of the acrylic resin composition is measured by a Vickers hardness test conducted under measurement conditions of maximum load 0.2 mN and holding time 10 seconds in accordance with JIS Z 2244 (2003). The acrylic resin composition according to any one of claims 25 to 33, which is 60% or more.
A frame, a light source, and a diffractive optical element according to any one of claims 1 to 12, further comprising: An illumination device, wherein the light source is fixed and connected to the conduction portion, and the diffractive optical element is disposed in the opening.
The lighting device according to claim 35, wherein the light source is a light source that emits infrared light having a wavelength of 780 nm or more.